Магнитный фазовый переход в MnSi на основе LSDA+U +SO-расчетов электронной структуры и спин-флуктуационной теории

AbstractSpin states appearing near the magnetic phase transition in helicoidal ferromagnet MnSi are studied on the basis of the spin-fluctuation theory and the LSDA + U + SO calculations of the electronic structure. The temperature dependence of the uniform magnetic susceptibility is calculated near the magnetic phase transition temperature, and the result agrees well with the experiment. Spin correlators corresponding to various solutions of the equation of magnetic state are determined in the region of the magnetic phase transition expanded in temperature. It is shown that, in this region, a helicoidal short-range order appears in the form of the superposition of left and right spin spirals with stochastic weight coefficients. It is shown that the magnetic susceptibility divergences on the helicoid wave vector at the temperature of disappearance of local magnetization and during the transition to the paramagnetic state.

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Magnetic Phase Transition in MnSi Based on the First Principle Calculations of Electronic Structure and Spin Fluctuation Theory

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.289.198 ◽

2019 ◽

Vol 289 ◽

pp. 198-204

Author(s):

Aleksandr Povzner ◽

Tatyana A. Nogovitsyna ◽

Arkadij G. Volkov ◽

Tagir Nuretdinov

Keyword(s):

Phase Transition ◽

Electronic Structure ◽

Magnetic Phase Transition ◽

Magnetic Phase ◽

Spin Fluctuation ◽

Fluctuation Theory ◽

Ministry Of Education ◽

Spin Correlations ◽

The Russian Federation ◽

Good Agreement

Based on the spin-fluctuation theory and LSDA + U + SO-calculations of the electronic structure, the spin states arising in the region of the magnetic phase transition in the helicoidal ferromagnet MnSi are studied. Within the framework of the stated model of the electronic structure, a temperature dependence of the homogeneous magnetic susceptibility is obtained near the temperature of the magnetic phase transition, which is in good agreement with experiment. At the temperature of the transition to the paramagnetic state, the left chirality vanishes, and spin correlations arise with a radius equal to the length of the spin helix, which then decreases with temperature. The results were obtained within the framework of the assignment of the Ministry of Education and Science of the Russian Federation, contract 3.9521.2017 / 8.9

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Zero-field magnetic susceptibility study of the magnetic phase transition in the two-dimensional ionic ferromagnet bis(benzylammonium) tetrabromochromate(II), (C6H5CH2NH3)2CrBr4

Inorganic Chemistry ◽

10.1021/ic00248a037 ◽

1987 ◽

Vol 26 (1) ◽

pp. 191-194 ◽

Cited By ~ 28

Author(s):

Carlo Bellitto ◽

Pasquale Filaci ◽

Salvatore Patrizio

Keyword(s):

Phase Transition ◽

Magnetic Susceptibility ◽

Magnetic Phase Transition ◽

Magnetic Phase ◽

Zero Field ◽

Two Dimensional ◽

Susceptibility Study ◽

Magnetic Susceptibility Study

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A.C. magnetic susceptibility determination of magnetic phase transition in NiCl2 · 6H2O

Physics Letters A ◽

10.1016/0375-9601(73)90937-7 ◽

1973 ◽

Vol 44 (1) ◽

pp. 13-14 ◽

Cited By ~ 8

Author(s):

C.Castilla Becerra ◽

A.Paduan Filho

Keyword(s):

Phase Transition ◽

Magnetic Susceptibility ◽

Magnetic Phase Transition ◽

Magnetic Phase

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Электронная структура и магнитный фазовый переход в геликоидальных ферромагнетиках Fe-=SUB=-1-x-=/SUB=-Co-=SUB=-x-=/SUB=-Si

Физика твердого тела ◽

10.21883/ftt.2018.02.45372.232 ◽

2018 ◽

Vol 60 (2) ◽

pp. 227

Author(s):

А.А. Повзнер ◽

А.Г. Волков ◽

Т.А. Ноговицына

Keyword(s):

Magnetic State ◽

Magnetic Phase ◽

Coefficient Of Thermal Expansion ◽

State Equation ◽

Paramagnetic State ◽

Magnetic Contribution ◽

Local Magnetization ◽

Virtual Crystal Approximation ◽

Volume Coefficient ◽

Moriya Interaction

AbstractLSDA + U + SO calculations of the electronic structure of helicoidal Fe_1 - x Co_ x Si ferromagnets within the virtual crystal approximation have been supplemented with the consideration of the Dzyaloshinski-Moriya interaction and ferromagnetic fluctuations of the spin density of collective d electrons with the Hubbard interactions at Fe and Co atoms randomly distributed over sites. The magnetic-state equation in the developed model describes helicoidal ferromagnetism and its disappearance accompanied by the occurrence of a maximum of uniform magnetic susceptibility at temperature T _ C and chiral fluctuations of the local magnetization at T > T _ C . The reasons why the magnetic contribution to the specific heat at the magnetic phase transition changes monotonically and the volume coefficient of thermal expansion (VCTE) at low temperatures is negative and has a wide minimum near T _ C have been investigated. It is shown that the VCTE changes sign when passing to the paramagnetic state (at temperature T _ S ).

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