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The Splitting of SDW State into Commensurable and Incommensurables Ones and the Peculiarities of the Behavior of Thermodynamic Quantities in a Magnetic Field Arbitrarily Oriented to Magnetization in Quasi Two-Dimensional Systems

  • M. E. Palistrant
  • V. A. Ursu
  • M. Calalb
Original Paper

Abstract

The quasi-two-dimensional system in which magnetism is caused by spin density wave (SDW) with an anisotropic energy spectrum (with defined impurity concentration x) is examined. The wave vector \(\vec{Q}\) is supposed to be different from 2k F and the umklapp scattering (U-processes) is taken into account. The system is placed in a magnetic field arbitrarily oriented with respect to the vector \(\vec{M}_{Q}\). The basic equations for order parameters \(M_{Q}^{z}, M_{Q}', M_{z}, M^{\sigma}\) are obtained and the system of these equations is transformed taking into account the U-processes. The particular cases \(( \tilde{H} \Vert \vec{M}_{Q} )\) and \(( \tilde{H} \bot \vec{M}_{Q} )\) and the case of small arbitrarily oriented magnetic fields \(\vec{\tilde{H}}\) are examined in detail. The conditions of the system transition to commensurable and incommensurable SDW state are analyzed. The phase diagram (T,x) at H=0 is traced. The influence of the magnetic field \(\vec{\tilde{H}}\) on the temperature of magnetic transition is researched and the aspect of the phase diagram in magnetic field in the cases H z H σ =0 is presented. The longitudinal magnetic susceptibility χ which demonstrates that at x<x c the temperature behavior is similar to the case when the system has a gap, and at x>x c to a gapless case. At xx c in the dependence X (T) a local maximum appears. The influence of the energy spectrum anisotropy on the system’s properties is researched. Also the angular anisotropy of the quantity χ at different values of T and x is determined.

Keywords

Commensurable and incommensurable states of SDW Angular anisotropy Magnetic field Magnetic susceptibility 

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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.Institute of Applied Physics of Moldavian Academy of ScienceChisinauRepublic of Moldova
  2. 2.Tiraspol State UniversityChisinauRepublic of Moldova

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