The Zero Temperature Heisenberg Ferromagnet as a Field Theory

1969 ◽  
pp. 51-58
Author(s):  
Daniel A. Dubin
Keyword(s):  
Field Theory ◽  
Heisenberg Ferromagnet ◽  
Zero Temperature

Review of the holographic Lifshitz theory

2014 ◽  
Vol 29 (24) ◽  
pp. 1430049 ◽  
Author(s):  
Chanyong Park
Keyword(s):  
Field Theory ◽  
Finite Temperature ◽  
Quasinormal Mode ◽  
Thermodynamic Quantities ◽  
Black Brane ◽  
Zero Temperature ◽  
Hydrodynamic Properties ◽  
Relativistic Field ◽  
Thermal Entropy ◽  
Lifshitz Theory

We review interesting results achieved in recent studies on the holographic Lifshitz field theory. The holographic Lifshitz field theory at finite temperature is described by a Lifshitz black brane geometry. The holographic renormalization together with the regularity of the background metric allows to reproduce thermodynamic quantities of the dual Lifshitz field theory where the Bekenstein–Hawking entropy appears as the renormalized thermal entropy. All results satisfy the desired black brane thermodynamics. In addition, hydrodynamic properties are further reviewed in which the holographic retarded Green functions of the current and momentum operators are studied. In a nonrelativistic Lifshitz field theory, intriguingly, there exists a massive quasinormal mode at finite temperature whose effective mass is linearly proportional to temperature. Even at zero temperature and in the nonzero momentum limit, a quasinormal mode still remains unlike the dual relativistic field theory. Finally, we account for how adding impurity modifies the electric property of the nonrelativistic Lifshitz theory.

N-quantum approach to the BCS theory of superconductivity

1994 ◽  
Vol 72 (9-10) ◽  
pp. 574-577 ◽  
Author(s):  
O. W. Greenberg
Keyword(s):  
Field Theory ◽  
Finite Temperature ◽  
Bcs Theory ◽  
Zero Temperature ◽  
General Applicability ◽  
Finite Temperature Field Theory ◽  
Gap Equation ◽  
Quantum Approach ◽  
Quantized Field ◽  
Theory Of Superconductivity

A method of general applicability to the solution of second-quantized field theories at finite temperature is illustrated using the BCS (Bardeen–Cooper–Schrieffer) model of superconductivity. Finite-temperature field theory is treated using the thermo field-theory formalism of Umezawa and collaborators. The solution of the field theory uses an expansion in thermal modes analogous to the Haag expansion in asymptotic fields used in the N-quantum approximation at zero temperature. The lowest approximation gives the usual gap equation.

scholarly journals Finite spatial volume approach to finite temperature field theory

1981 ◽  
Vol 59 (8) ◽  
pp. 967-973 ◽  
Author(s):  
Nathan Weiss
Keyword(s):  
Field Theory ◽  
Finite Temperature ◽  
Gauge Theories ◽  
Relativistic Quantum ◽  
Free Field ◽  
Spatial Dimension ◽  
Zero Temperature ◽  
Relativistic Quantum Field Theory ◽  
Spatial Volume ◽  
The Relationship

A relativistic quantum field theory at finite temperature T = β−1 is equivalent to the same field theory at zero temperature but with one spatial dimension of finite length β. This equivalence is discussed for scalars, for fermions, and for gauge theories. The relationship is checked for free field theory. The translation of correlation functions between the two formulations is described with special emphasis on the nonlocal order parameters of gauge theories. Possible applications are mentioned.

Spontaneous magnetization of ferromagnet in mean-field Heisenberg model

2019 ◽  
Vol 33 (04) ◽  
pp. 1950036 ◽  
Author(s):  
Artur P. Durajski ◽  
Anna B. Olesik ◽  
Anita E. Auguscik
Keyword(s):  
Field Theory ◽  
Magnetic Susceptibility ◽  
Curie Temperature ◽  
Heisenberg Model ◽  
Spontaneous Magnetization ◽  
Mean Field Theory ◽  
Mean Field ◽  
Function Technique ◽  
Heisenberg Ferromagnet ◽  
Temperature Dependences

The Heisenberg ferromagnet model has been studied theoretically using the Weiss mean-field theory and Green’s function technique. The equations for the Curie temperature, magnetization, and magnetic susceptibility were analytically derived. Moreover, we proved, that our results are useful in description of real materials. The calculated value of Curie temperature for [Formula: see text] alloy correspond well with the experimental results obtained recently on the base of the temperature dependences of magnetization.

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