/ N. V. Volkov [et al.]> // J. Phys.: Condens. Matter. - 2008. -
Vol. 20,
Is. 44. - Ст. 445214,
DOI 10.1088/0953-8984/20/44/445214. - Cited References: 11. - This study was supported by the INTAS (project No 061000013-9002), the Division of Physical Sciences of RAS, program `Spin-dependent Effects in Solids and Spintronics' (project No. 2.4.2 of SB RAS), the President of the Russian Federation, grant for Support of Leading Scientific Schools (project No. NSh-1011.2008.2), KRSF-RFBR `Enisey2007', project No. 07-02-96801-a, and the Siberian Branch of RAS, Integration project No. 3.7.
. - ISSN 0953-8984
РУБ Physics, Condensed Matter
Аннотация: We present the results of a heat capacity study of Pb(3)Mn(7)O(15) single crystals with approximately equal concentrations of Mn(3+) and Mn(4+) ions. In the temperature interval between 210 and 260 K, an excess heat capacity of nonmagnetic origin, most likely associated with the process of charge localization, has been observed. Also, three pronounced anomalies corresponding to the changes in a magnetic subsystem of the crystal have been observed in the temperature dependence of the heat capacity. A broad hump near 150 K is related to the formation of a short-range magnetic order. This process of short-range ordering is rather prominent, considering the appreciable value of the entropy loss accompanying the change in the magnetic state. A clear lambda-shaped peak at 70 K marks the onset of a long-range antiferromagnetic order. Another anomalous contribution to the heat capacity of magnetic origin has been revealed at temperatures below 20 K. This contribution is associated with a magnetic transition of an unknown nature, which is also clearly evident in magnetization versus temperature curves. The total magnetic contribution to the entropy deduced from the actual experimental data over the entire temperature range is much smaller than is expected for a completely ordered Mn spin system in the crystal. We suggest several possible reasons that may account for this `missing' entropy.
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Держатели документа: [Volkov, N. V.
Sablina, K. A.
Eremin, E. V.
Flerov, I. N.
Kartashev, A.] RAS, SB, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Volkov, N. V.
Flerov, I. N.] Siberian Fed Univ, Dept Phys, Krasnoyarsk 660041, Russia
[Boeni, P.] Tech Univ Munich, Dept Phys E21, D-85747 Garching, Germany
[Shah, V. R.] Indiana Univ, Dept Phys, Bloomington, IN 47405 USA
[Rasch, J. C. E.
Boehm, M.] Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France
[Rasch, J. C. E.
Schefer, J.] Swiss Fed Inst Technol, Neutron Scattering Lab, CH-5232 Villigen, Switzerland
[Rasch, J. C. E.
Schefer, J.] Paul Scherrer Inst, CH-5232 Villigen, Switzerland
ИФ СО РАН
Kirensky Institute of Physics, SB, RAS, 660036 Krasnoyarsk, Russian Federation
Department of Physics, Siberian Federal University, 660041 Krasnoyarsk, Russian Federation
Physics Department E21, Technical University of Munich, D-85747 Garching, Germany
Physics Department, Indiana University, Bloomington, IN 47405, United States
Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, Cedex 9, France
Laboratory for Neutron Scattering, ETH Zurich, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
Доп.точки доступа: Volkov, N. V.; Волков, Никита Валентинович; Sablina, K. A.; Саблина, Клара Александровна; Eremin, E. V.; Еремин, Евгений Владимирович; Boni, P.; Shah, V. R.; Flerov, I. N.; Флёров, Игорь Николаевич; Kartashev, A.; Rasch, JCE; Boehm, M.; Schefer, J.