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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Valkov V. V., Valkova T. A.
Заглавие : Application of indefinite metric for transition to bose description of Su(3) hamiltonians - excitation spectrum of spin nematics
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz. - 1991. - Vol. 99, Is. 6. - P.1881-1897. - ISSN 0044-4510
Примечания : Cited References: 37
Предметные рубрики: BIQUADRATIC EXCHANGE
PHASE-TRANSITIONS
DIAGRAM TECHNIQUE
MAGNETISM
FIELD
STATE
Аннотация: A procedure is developed for a correct transition to the Bose representation for quantum SU(3) Hamiltonians. The analysis is carried out for a spin nematic by applying the indefinite metric formalism and pseudo-Hubbard operators. An important aspect of the theory is that the finiteness of the number of physical states is taken into account. This is attained by introducing and consistently taking into account the metric operator for which purpose a simple expression in terms of Bose operators is suggested. It is shown that in this approach the quantum Bose analog of the Hamiltonian is an Hermitian operator. This circumstance removes a number of principle contradictions which appeared previously on application of the Bose analog of the Hamiltonian derived by virtually identifying the Hubbard and pseudo-Hubbard operators and ignoring the finiteness of the number of physical states. The integral equations defining the chief characteristics of the system are obtained and solved analytically for the spin-nematic state of a magnet with S = 1 and by taking into account anharmonic effects. This permits one to write down in nonlinear theory explicit expressions for the two branches of the quantum excitation spectrum. The character of the renormalization of the spectrum parameters due to the presence of zero-point quantum oscillations is studied. The renormalization of the critical field on transition of the system from the spin nematic state is calculated analytically.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : GEKHT R. S.
Заглавие : MAGNETIC-STRUCTURES AND PROPERTIES OF STATES IN STRONGLY FRUSTRATED HEISENBERG ANTIFERROMAGNETS
Место публикации : Zhurnal Eksperimentalnoi Teor. Fiz.: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 102, Is. 6. - P1968-1982. - ISSN 0044-4510
Примечания : Cited References: 23
Предметные рубрики: PHASE-TRANSITIONS
SPIN
LATTICE
MODELS
LONG
Аннотация: The magnetic structures and properties of states in frustrated Heisenberg antiferromagnets are analyzed. It is shown that frustrations induced due to additional spins in the system lead to a large variety of phase with the commensurable and uncommensurable periods and also to arising nonperiodical phases. The energy spectrum of states is studied. It is found that in the large region of the frustration parameter variation the modulated phase (0, Q) is unstable. The phase diagram of states is found and the region of local degeneration for some structures is indicated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : GEKHT R. S., GRISHIN V. V.
Заглавие : ON MAGNETIC STATES IN STRONGLY FRUSTRATED 2-DIMENSIONAL ANTIFERROMAGNETICS
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1992. - Vol. 34, Is. 11. - P3557-3559. - ISSN 0367-3294
Примечания : Cited References: 5
Предметные рубрики: PHASE-TRANSITIONS
LATTICE
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : GEKHT R. S., PONOMAREV V. I.
Заглавие : LOW-TEMPERATURE PROPERTIES OF QUASI-2-DIMENSIONAL FRUSTRATED ANTI-FERROMAGNETICS
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 11. - P3394-3397. - ISSN 0367-3294
Примечания : Cited References: 8
Предметные рубрики: PHASE-TRANSITIONS
MAGNETIC STATES
ANTIFERROMAGNETS
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zeer E. P., Falaleev O. V., Ivanov Y. N., Petrakovskaya E. A.
Заглавие : Study of molecular mobility in ABF6-center-dot-6H2O crystal family
Место публикации : Fiz. Tverd. Tela. - 1994. - Vol. 36, Is. 8. - P.2210-2220. - ISSN 0367-3294
Примечания : Cited References: 21
Предметные рубрики: PHASE-TRANSITIONS
NMR
SYSTEM
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gekht R. S., Epikhin A. M., Ponomarev V. I.
Заглавие : Helicoidal magnetic structure in frustrated antiferromagnetics
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1995. - Vol. 37, Is. 6. - P.1891-1893. - ISSN 0367-3294
Примечания : Cited References: 6
Предметные рубрики: QUANTUM FLUCTUATIONS
PHASE-TRANSITIONS
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanov Y. N., Totz J., Michel D., Klotzsche G., Sukhovsky A. A., Aleksandrova I. P.
Заглавие : Chemical exchange in NH4HSeO4 single crystals studied by two-dimensional H-2 nuclear magnetic resonance
Разночтения заглавия :авие SCOPUS: Chemical exchange in NH4HSeO4 single crystals studied by two-dimensional 2H nuclear magnetic resonance
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 1999. - Vol. 11, Is. 18. - P.3751-3760. - ISSN 0953-8984, DOI 10.1088/0953-8984/11/18/310
Примечания : Cited References: 16
Предметные рубрики: PHASE-TRANSITIONS
CONDUCTIVITY PROCESSES
AMMONIUM
Ключевые слова (''Своб.индексиров.''): hydrogen bonds--nuclear magnetic resonance--single crystals--thermal effects--ammonium hydrogen selenate--ammonium compounds
Аннотация: Processes of chemical exchange of deuterons in partially deuterated ammonium hydrogen selenate, NH4HSeO4 (AHSe), crystals are investigated by means of H-2 nuclear magnetic resonance (NMR) experiments over a wide temperature range. The temperature dependencies of the quadrupole line splittings in the one-dimensional spectra of AHSe above 350 K revealed lineshape changes which are characteristic for chemical exchange processes. A detailed study of these exchange processes in AHSe is achieved by means of two-dimensional H-2 NMR experiments. In the temperature range investigated, a chemical exchange occurs only between those deuteron (proton) sites which are involved in hydrogen bonds (alpha- and beta-positions). It was established that the rates of exchange between all types of hydrogen-bound deuteron are approximately the same. Exchange between these positions and the deuterons in the ND4 groups could not be detected. On the basis of our findings, we finally discuss a model for the microscopic mechanism of hydrogen transport in AHSe.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G.
Заглавие : Application of synchrotron radiation to the study of magnetic materials
Место публикации : Uspekhi Fiz. Nauk: MEZHDUNARODNAYA KNIGA, 1999. - Vol. 169, Is. 8. - P.869-887. - ISSN 0042-1294
Примечания : Cited References: 93
Предметные рубрики: X-RAY-SCATTERING
RESONANCE EXCHANGE SCATTERING
RARE-EARTH-METALS
CIRCULAR-DICHROISM
VALENCE STATES
CO/PD(111) MULTILAYERS
ABSORPTION-SPECTRA
PHASE-TRANSITIONS
SPIN POLARIZATION
EDGE STRUCTURE
Аннотация: The recent results of the studies of magnetic materials using synchrotron irradiation are reviewed. The influence of magnetic effects on X-ray scattering is studied for linearly and circularly polarized photons, and effects of magnetic circular dichroism on the spectra of X-ray absorption and photoelectron emission are discussed. It is shown that X-ray magnetooptics techniques provide fine details of crystal and magnetic structures and also make it possible to separate the spin and orbital contributions to the total moment; to obtain element- and position-sensitive information on the magnetic properties of the material; to visualize domains and domain walls; and to probe magnetization reversal dynamics. A comparison of magnetic neutron and X-ray methods is given.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Afanas'ev M. L., Ushakova T. V.
Заглавие : Thermodynamic properties of (NH4)(2)KGaF6 elpasolite
Разночтения заглавия :авие SCOPUS: Thermodynamic properties of (NH4)2KGaF6 elpasolite
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2001. - Vol. 43, Is. 12. - P2301-2306. - ISSN 1063-7834, DOI 10.1134/1.1427960
Примечания : Cited References: 19
Предметные рубрики: NUCLEAR MAGNETIC-RESONANCE
PHASE-TRANSITIONS
CRYOLITE (NH4)(3)SCF6
MOTIONS
F-19
H-1
Аннотация: The heat capacity of (NH4)(2)KGaF6 elpasolite is measured in the temperature range from 80 to 350 K. A sequence of three phase transitions at T-1 = 288.5 K, T-2 = 250 K, and T-3 = 244.5 K is revealed, and the thermodynamic characteristics of these transitions are determined. The influence of hydrostatic pressure on the phase transition temperature is investigated. The results obtained are discussed within the model of orientational ordering of NH4+ and GaF63- ionic groups. (C) 2001 MAIK "Nauka/Interperiodica".
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Burriel R., Gorev M. V., Isla P., Voronov V. N.
Заглавие : Low-temperature specific heat of the Rb2KScF6 elpasolite
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 1. - P167-170. - ISSN 1063-7834, DOI 10.1134/1.1537430
Примечания : Cited References: 9
Предметные рубрики: PHASE-TRANSITIONS
CRYOLITE (NH4)(3)SCF6
DISTORTED PHASES
SYMMETRY
Аннотация: The specific heat of single-crystal Rb2KScF6 is measured using ac calorimetry in the range 4-280 K. The results are discussed in the context of a group-theoretical analysis of possible distortions of the elpasolite structure and of experimental data obtained earlier with an adiabatic calorimeter in a narrower temperature region. (C) 2003 MAIK "Nauka/Interperiodica".
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Bovina A. F., Laptash N. M.
Заглавие : Calorimetric and x-ray diffraction studies of the (NH4)(3)WO3F3 and (NH4)(3)TiOF5 perovskite-like oxyfluorides
Разночтения заглавия :авие SCOPUS: Calorimetric and X-ray diffraction studies of the (NH4)3WO 3F3 and (NH4)3TiOF5 perovskite-like oxyfluorides
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 5. - P915-921. - ISSN 1063-7834, DOI 10.1134/1.1744971
Примечания : Cited References: 11
Предметные рубрики: PHASE-TRANSITIONS
ELPASOLITE
K3MOO3F3
Аннотация: The heat capacity and unit cell parameters of the (NH4)(3)WO3F3 and (NH4)(3)TiOF5 perovskite-like oxyfluorides were measured in the temperature interval from 80 to 300 K; the existence of two and one phase transitions in these compounds, respectively, was demonstrated, and their thermodynamic parameters were determined. The effect of a hydrostatic pressure of up to 0.5 GPa on the phase transition temperatures was studied. Triple points and high-pressure phases were found in the T vs. p diagrams. An analysis of entropy changes suggests that all the structural transformations revealed are associated with the ordering of structural blocks. (C) 2004 MAIK "Nauka / Interperiodica".
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Kartashev A. V., Mel'nikova S. V.
Заглавие : Calorimetric and optical studies of orthorhombic and cubic CsLiCrO4 crystals
Разночтения заглавия :авие SCOPUS: Calorimetric and optical studies of orthorhombic and cubic CsLiCrO 4 crystals
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2006. - Vol. 48, Is. 11. - P2171-2176. - ISSN 1063-7834, DOI 10.1134/S1063783406110242
Примечания : Cited References: 23
Предметные рубрики: PHASE-TRANSITIONS
X-RAY
NH4LISO4
ALPHA
Аннотация: Careful calorimetric and polarization optical studies of a metastable cubic modification of a CsLiCrO4 crystal (space group (F43m)) are performed. Anomalies of the heat capacity indicative of structural distortions at 92.4 and 69.1 K were revealed, and the values of the thermodynamic parameters of the phase transitions were determined. The crystal twinning in the intermediate phase was studied. A comparative analysis of the phase transitions occurring in a series of ALiMO(4) crystals (A=NH4, Cs; M=S, Cr, Mo, W) was performed. First studies of the monotropic structural transformation F43m - Pmcn and the enantiotropic phase transition Pmcn reversible arrow P112(1)/n were carried out using scanning calorimetry, and the thermodynamic parameters of these transitions were determined.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrov K. S., Vtyurin A. N., Gerasimova J. V., Krylov A. S., Laptash N. M., Voyt E. I., Kocharova A. G., Surovtsev S. V.
Заглавие : Raman spectra and ordering processes in alcaline-tungsten oxyfluorides
Коллективы : Russian-CIS-Baltic-Japanese symposium on ferroelectricity
Место публикации : Ferroelectrics: Taylor & Francis LTD, 2007. - Vol. 347. - P.79-85. - ISSN 0015-0193, DOI 10.1080/00150190601187070
Примечания : Cited References: 8
Предметные рубрики: PHASE-TRANSITIONS
ELPASOLITES
Аннотация: Raman spectra of perovskite-like (NH4)(3)WO3F3 (assigned below as A3), (NH4)(2)KWO3F3 (A2K), Cs-2(NH4)WO3F3 (C2A) oxyfluorides are obtained in a wide temperature range including transition points for A3 and A2 K crystals. Transition anomalies are found and analyzed. Transformation in A3 crystal is shown to be bound with octahedron groups ordering and H-bond formation, that is accompanied by cell volume multiplication, hardening and formation of complex discrete low frequency lattice spectrum. Same cell doubling was found in A2 K crystal, but without lattice ordering. C2A lattice stays disordered down to 15 K.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Fokina V. D., Gorev M. V., Bogdanov E. V., Molokeev M. S., Bovina A. F., Kocharova A. G.
Заглавие : Effect of deuteration on the thermal properties and structural parameters of the (NH4)(2)WO2F4 oxyfluoride
Разночтения заглавия :авие SCOPUS: Effect of deuteration on the thermal properties and structural parameters of the (NH4)2WO2F4 oxyfluoride
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 6. - P1149-1156. - ISSN 1063-7834, DOI 10.1134/S1063783407060212
Примечания : Cited References: 11
Предметные рубрики: PEROVSKITE-LIKE OXYFLUORIDES
PHASE-TRANSITIONS
(NH4)(3)WO3F3
(NH4)(3)TIOF5
Аннотация: The thermal properties and structure of (ND4)(2)WO2F4 crystals are investigated. It is established that deuteration does not lead to a change in the symmetry of the initial phase Cmcm but considerably decreases the extent of its disordering, which, in turn, brings about a substantial decrease in the phase transition entropy. Apart from the anomalies associated with phase transitions characteristic of the protonic compound, the heat capacity exhibits two additional anomalies. Analysis of the phase diagram of the deuterated crystal reveals a triple point at a pressure p = 0.18 GPa, which is predicted for (NH4)(2)WO2F4 at about 0.7 GPa.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Mikhaleva E. A.
Заглавие : Electrocaloric effect and anomalous conductivity of the ferroelectric NH4HSO4
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 3. - P478-484. - ISSN 1063-7834, DOI 10.1134/S1063783408030141
Примечания : Cited References: 10
Предметные рубрики: PHASE-TRANSITIONS
Аннотация: An intensive electrocaloric effect in the uniaxial ferroelectric NH4HSO4 near the second-order phase transition (T-1 approximate to 271 K) is studied. A high electrical conductivity of the NH4HSO4 crystal is revealed, and its temperature dependence is investigated. The results obtained are analyzed together with the data available for the ferroelectrics, which hold promise for the use as solid-state cooling agents.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I. P., Sukhovskii A. A., Ivanov Y. N., Yablonskaya Y. E., Vakhrushev S. B.
Заглавие : Na-23 NMR study of the local order in the Na1/2Bi1/2TiO3 structure in a weak magnetic field
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 50, Is. 3. - P496-501. - ISSN 1063-7834, DOI 10.1134/S1063783408030177
Примечания : Cited References: 14
Предметные рубрики: PHASE-TRANSITIONS
PEROVSKITE
Аннотация: The orientation dependences of the second-order quadrupole shifts of the central component in the Na-23 NMR spectrum were studied in the temperature range 293-760 K. The profile of the spectral distribution is calculated using various models of the Na1/2Bi1/2TiO3 structure. The calculations agree with the experimental data for the monoclinic structure of a polar cluster with two Na displacement components: a displacement along the [111](P) direction and a small displacement statistically or dynamically disordered over six equally probable [100](P)-type directions. Tetragonal-phase nuclei and monoclinic clusters with a very small displacement component along the [111](P) direction are found to coexist and have close energies over the temperature range 580-610 K. The results obtained provide new information concerning the character of the diffuse phase transition at 610 K.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shneyder E. I., Ovchinnikov S. G.
Заглавие : Isotope effect in the model of strongly correlated electrons with the magnetic and phonon superconducting pairing mechanisms
Коллективы : Presidium of the Russian Academy of Sciences [40]; Russian Academy of Sciences; Russian Foundation for Basic Research [09-02-00127]
Место публикации : J. Exp. Theor. Phys. - 2009. - Vol. 109, Is. 6. - P.1017-1021. - ISSN 1063-7761, DOI 10.1134/S1063776109120139
Примечания : Cited References: 42. - This study was financed under programs 5.7 and "Quantum Physics of Condensed Matter" of the Presidium of the Russian Academy of Sciences, integration project no. 40 of the Siberian Branch and Ural Division of the Russian Academy of Sciences, and the Russian Foundation for Basic Research (project no. 09-02-00127).
Предметные рубрики: CUPRATE SUPERCONDUCTORS
PHASE-TRANSITIONS
3-CENTER INTERACTIONS
HUBBARD-MODEL
TEMPERATURE
LA2-XSRXCUO4
SYMMETRY
EXCHANGE
COPPER
BI2SR2CACU2O8+DELTA
Ключевые слова (''Своб.индексиров.''): ab initio calculations--calculated values--cooper pairing--isotope effect--magnetic mechanisms--order of magnitude--pairing mechanism--phonon mechanism--strongly correlated electrons--superconducting pairing mechanism--superconducting state--type theory--carrier mobility--electron-phonon interactions--isotopes--superconductivity--superconducting magnets
Аннотация: Peculiarities of the temperature isotope effect in a BCS-type theory describing the exchange and phonon mechanisms of Cooper pairing in a system of strongly correlated electrons are considered. The electron-phonon interaction constant is determined from the fitting of the calculated value of the isotope-effect index to the observed value with the parameters of La(2 - x) Sr (x) CuO(4) obtained from ab initio calculations. The value of this constant indicates that the contribution from the traditional pairing mechanism to the superconducting state is of the same order of magnitude as the contribution from the magnetic mechanism.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chaudhury R. P., Yen F., Lorenz B., Sun Y. Y., Bezmaternykh L. N., Temerov V. L., Chu C. W.
Заглавие : Magnetoelectric effect and spontaneous polarization in HoFe3(BO3)(4) and Ho0.5Nd0.5Fe3(BO3)(4)
Коллективы : NSF [DMR9804325]; Temple Foundation; State of Texas through the TC-SUH; DoE
Разночтения заглавия :авие SCOPUS: Magnetoelectric effect and spontaneous polarization in HoFe3 (BO3) 4 and Ho0.5 Nd0.5 Fe3 (BO 3) 4
Место публикации : Phys. Rev. B. - 2009. - Vol. 80, Is. 10. - Ст.104424. - ISSN 1098-0121, DOI 10.1103/PhysRevB.80.104424
Примечания : Cited References: 35. - This work is supported in part by NSF Grant No. DMR9804325, the T. L. L. Temple Foundation, the J.J. and R. Moores Endowment, and the State of Texas through the TC-SUH and at LBNL by the DoE.
Предметные рубрики: IRON BORATE GDFE3(BO3)(4)
PHASE-TRANSITIONS
NDFE3(BO3)(4)
MULTIFERROICS
Аннотация: The thermodynamic, magnetic, dielectric, and magnetoelectric properties of HoFe3(BO3)(4) and Ho0.5Nd0.5Fe3(BO3)(4) are investigated. Both compounds show a second order Neel transition above 30 K and a first-order spin reorientation transition below 10 K. HoFe3(BO3)(4) develops a spontaneous electrical polarization below the Neel temperature (T-N) which is diminished in external magnetic fields. No magnetic-field induced increase of the polarization could be observed in HoFe3(BO3)(4). In contrast, the solid solution Ho0.5Nd0.5Fe3(BO3)(4) exhibits both, a spontaneous polarization below T-N and a positive magnetoelectric effect at higher fields that extends to high temperatures. The superposition of spontaneous polarization, induced by the internal magnetic field in the ordered state, and the magnetoelectric polarizations due to the external field results in a complex behavior of the total polarization measured as a function of temperature and field.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Eremin I., Efremov D. V., Maslov D. L., Chubukov A. V.
Заглавие : Nonanalytic Spin Susceptibility of a Fermi Liquid: The Case of Fe-Based Pnictides
Коллективы : RFBR [09-02-00127]; OFN RAS; APCTP; NSF-DMR [0645461, 0604406]; RMHE [2.1.1/3199]; Laboratoire de Physique des Solides, Universite Paris-Sud (France); RTRA Triangle de la Physique
Разночтения заглавия :авие SCOPUS: Nonanalytic spin susceptibility of a fermi liquid: The case of Fe-based pnictides
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2009. - Vol. 102, Is. 23. - Ст.236403. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.102.236403
Примечания : Cited References: 41. - We thank R. Klingeler for useful discussions. M. M. K. acknowledges support from RFBR ( 09-02-00127) and the OFN RAS program on "Strong electronic correlations". I. E. acknowledges partial support from APCTP, NSF-DMR ( 0645461), and the RMHE Program ( Contract No. 2.1.1/3199). D. L. M. acknowledges support from Laboratoire de Physique des Solides, Universite Paris-Sud ( France) and RTRA Triangle de la Physique. A. V. C. acknowledges support from NSF-DMR 0604406.
Предметные рубрики: PHASE-TRANSITIONS
QUANTUM
Ключевые слова (''Своб.индексиров.''): electron pockets--fermi energy--linear temperature dependence--pnictides--prefactor--quantitative agreement--spin susceptibility--temperature dependence--fermi liquids--fermions--liquids--magnetic susceptibility--temperature distribution--spin dynamics
Аннотация: We propose an explanation of the peculiar linear temperature dependence of the uniform spin susceptibility chi(T) in ferropnictides. We argue that the linear in T term appears to be due to the nonanalytic temperature dependence of chi(T) in a two-dimensional Fermi liquid. We show that the prefactor of the T term is expressed via the square of the spin-density-wave (SDW) amplitude connecting nested hole and electron pockets. Because of an incipient SDW instability, this amplitude is large, which, along with a small value of the Fermi energy, makes the T dependence of chi(T) strong. We demonstrate that this mechanism is in quantitative agreement with the experiment.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Janoschek M., Fischer P., Schefer J., Roessli B., Pomjakushin V., Meven M., Petricek V., Petrakovskii G. A., Bezmaternykh L. N.
Заглавие : Single magnetic chirality in the magnetoelectric NdFe3((BO3)-B-11)(4)
Разночтения заглавия :авие SCOPUS: Single magnetic chirality in the magnetoelectric NdFe3( 11BO3 )4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2010. - Vol. 81, Is. 9. - Ст.94429. - ISSN 1098-0121, DOI 10.1103/PhysRevB.81.094429
Примечания : Cited References: 55
Предметные рубрики: NEUTRON-DIFFRACTION
PHASE-TRANSITIONS
SLOW-NEUTRONS
CRYSTAL
NDFE3(BO3)(4)
EXTINCTION
NUCLEAR
ORDER
MNSI
ANTIFERROMAGNETS
Аннотация: We have performed an extensive study of single crystals of the magnetoelectric NdFe3 ((BO3)-B-11)(4) by means of a combination of single-crystal neutron diffraction and spherical neutron polarimetry. Our investigation did not detect significant deviations at low temperatures from space group R32 concerning the chemical structure. With respect to magnetic ordering our combined results demonstrate that in the commensurate magnetic phase below T-N approximate to 30 K all three magnetic Fe moments and the magnetic Nd moment are aligned ferromagnetically in the basal hexagonal plane but align antiferromagnetically between adjacent planes. The phase transition to the low-temperature incommensurate (IC) magnetic structure observed at T-IC approximate to 13.5 K appears to be continuous. By means of polarized neutron studies it could be shown that in the incommensurate magnetic phase the magnetic structure of NdFe3((BO3)-B-11)(4) is transformed into a long-period antiferromagnetic helix with single chirality. Close to the commensurate-incommensurate phase transition third-order harmonics were observed, which in addition indicate the formation of magnetic solitons.
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