Bose Liquid Mean-Field Theory with Application to HeI

2019 ◽  
Vol 26 (02) ◽  
pp. 1950005
Author(s):  
Jan Maćkowiak
Keyword(s):  
Field Theory ◽  
Heat Capacity ◽  
Temperature Dependence ◽  
Mean Field Theory ◽  
Mean Field ◽  
Liquid Structure ◽  
Experimental Plot ◽  
Bose Liquid ◽  
Ordered Motion ◽  
Good Agreement

A mean-field theory is developed for a Bose liquid enclosed in a large vessel 𝒱. In accord with liquid structure concepts of Mitus et al., the liquid in 𝒱 is assumed to consist of adjacent macroscopic subregions Λk. In each subregion the bosons perform a locally ordered motion with prevailing orientation k + x, which varies randomly when passing from one subregion to another. |k| is constant, whereas temperature dependence of |x| is governed by a mean-field theory (MFT). The theory is applied to simulate HeI heat capacity CV (T) at T > Tλ = 2.17 K and CV (T) singularity at [Formula: see text]. The MFT numerical heat capacity Cn(T) = ΔE/ΔT exhibits behaviour characteristic of a singularity at [Formula: see text]: rapid increase with decreasing ΔT. Apart from [Formula: see text], good agreement of Cn(T) with CV(T) experimental plot is also found above Tλ, at T ∊ (Tλ, 3K].

scholarly journals Magnetocaloric Effect in Nanosystems Based on Ferromagnets with Different Curie Temperatures

2021 ◽  
Vol 132 (1) ◽  
pp. 79-93
Author(s):  
M. A. Kuznetsov ◽  
A. B. Drovosekov ◽  
A. A. Fraerman
Keyword(s):  
Field Theory ◽  
Magnetocaloric Effect ◽  
Landau Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Maxwell Relation ◽  
Magnetic Cooling ◽  
The Mean ◽  
Curie Temperatures ◽  
Good Agreement

Abstract The magnetocaloric effect in nanosystems based on exchange-coupled ferromagnets with different Curie temperatures is calculated within the mean-field theory. Good agreement between the results of the mean-field theory and the Landau theory, valid near the critical phase transition temperature, is demonstrated for a flat-layered Fe/Gd/Fe structure. We show that a high magnetic cooling efficiency in this system is attainable in principle and prove the validity of the Maxwell relation, enabling an experimental verification of the predictions made. The theory developed for flat-layered structures is generalized to a granular medium.

THEORETICAL INVESTIGATION OF ASYMMETRIC SIMPLE EXCLUSION PROCESSES WITH OFF-RAMP ON THE BOUNDARIES

2012 ◽  
Vol 26 (24) ◽  
pp. 1250155 ◽  
Author(s):  
SONG XIAO ◽  
SHUYING WU ◽  
LIQIONG TANG ◽  
DONGSHENG ZHENG ◽  
JING SHANG
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Computer Simulations ◽  
Mean Field Theory ◽  
Mean Field ◽  
Exclusion Processes ◽  
Density Profiles ◽  
Asymmetric Simple Exclusion ◽  
Simple Exclusion ◽  
Good Agreement

In this letter, asymmetric simple exclusion processes with off-ramp on the boundaries have been studied by asymmetric simple exclusion processes (ASEPs). In this model, particles can only detach from a single off-ramp on the boundaries of the system. The phase diagrams and density profiles are calculated by approximate mean field theory and have shown good agreement with the extensive Monte Carlo computer simulations.

Mott Transition in the Mass Imbalanced Ionic Hubbard Model at Half Filling

2019 ◽  
Vol 29 (3SI) ◽  
pp. 305
Author(s):  
Nguyen Thi Hai Yen ◽  
Le Duc Anh ◽  
Hoang Anh Tuan ◽  
Nguyen Toan Thang
Keyword(s):  
Field Theory ◽  
Hubbard Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dynamical Mean Field Theory ◽  
Mass Imbalance ◽  
Half Filling ◽  
Ionic Hubbard Model ◽  
Ionic Energy ◽  
Good Agreement

The Mott - Hubbard metal - insulator transition in the half-filled mass imbalanced ionic Hubbard model is investigated using the two-site dynamical mean field theory. We find that for a fixed mass imbalanced parameter r the critical interaction Uc increases when the ionic energy \(\Delta\) is increased. In the other hand, for a fixed \(\Delta\), \(U_c\) decreases with increasing the mass imbalance. We also show the existence of BI phase in the system for the case \(\Delta \ne 0\), \(U=0\) and calculate the staggered charge density \(n_B − n_A\) as a function of the interaction for different values of the mass imbalance. Our results in the limiting cases (\(r = 1\); \(\Delta \ne 0\) or/and \(\Delta = 0\); \(r\ne 1\)) are in good agreement with those obtained from full dynamical mean field theory.

The nuclear relaxation rate for the itinerant-electron antiferromagnet

1982 ◽  
Vol 60 (5) ◽  
pp. 649-653 ◽  
Author(s):  
M. Crişan ◽  
Zs. Gulácsi
Keyword(s):  
Field Theory ◽  
Relaxation Rate ◽  
Mean Field Theory ◽  
Mean Field ◽  
Band Model ◽  
Itinerant Electron ◽  
Nuclear Relaxation ◽  
The Mean ◽  
Two Band Model ◽  
Good Agreement

The relaxation rate in the nuclear magnetic resonance of the itinerant-electron antiferromagnet was calculated as a function of temperature. A good agreement with the experimental results obtained on CrB2 has been observed. The two band model for the itinerant-electron antiferromagnet for T < TN (TN is the critical temperature) and the mean field theory for the critical region have been used to calculate [Formula: see text] as a function of temperature.

Tunneling Spectra of Inhomogeneous d-Wave Superconductor

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3484-3492
Author(s):  
Jung Hoon Han
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Low Energy ◽  
The Other ◽  
Tunneling Spectrum ◽  
Self Consistent ◽  
Underlying Disorder ◽  
D Wave ◽  
Good Agreement

The tunneling spectrum of an inhomogeneous d-wave superconductor is discussed in the framework of self-consistent slave-boson mean-field theory. Distinct from the usual BCS-type mean-field theory, an electron is now described using both fermionic and bosonic degree of freedom. We show that one can define two types of tunneling spectra in this theory, which also corresponds to two ways of calibrating the STM spectra. In good agreement with the experimental observation, we show that one type of tunneling spectrum remains inhomogeneous while the other type shows a remarkable degree of homogeneity at low energy, despite the underlying disorder. Physical implications of this result, in particular in relation to thermodynamic measurement such as heat capacity, are discussed.

Quantum tetrahedral mean-field theory of the pyrochlore lattice

2001 ◽  
Vol 79 (11-12) ◽  
pp. 1359-1364 ◽  
Author(s):  
A J García-Adeva ◽  
D L Huber
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Magnetic Susceptibility Data ◽  
Susceptibility Data ◽  
Starting Point ◽  
Theoretical Predictions ◽  
Magnetic Ions ◽  
The Individual ◽  
Good Agreement

A quantum mean-field theory of the pyrochlore lattice is presented. The starting point is not the individual magnetic ions, as in the usual Curie-Weiss mean-field theory, but a set of interacting corner-sharing tetrahedra. We check the consistency of the model against magnetic susceptibility data and find a good agreement between the theoretical predictions and the experimental data. Implications of the model and future extensions are also discussed. PACS Nos.: 75.10Jm, 75.30Cr, 75.40Cx

scholarly journals Influence of Uniform Compression on the Temperature Dependence of the Pseudogap of Medium-Praseodymium-Doped Y1−xPrxBa2Cu3O7−δ Single Crystals

2021 ◽  
Author(s):  
G. Ya. Khadzhai ◽  
A. Chroneos ◽  
Ι. L. Goulatis ◽  
S. N. Kamchatnaya ◽  
A. L. Chikina ◽  
...  
Keyword(s):  
Field Theory ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Mean Field Theory ◽  
Applied Pressure ◽  
Mean Field ◽  
Excess Conductivity ◽  
Uniform Compression ◽  
Exponential Temperature Dependence ◽  
The Mean

AbstractThe effect of high pressure on the conductivity in the basal plane of HTSC single crystals of Y0.77Pr0.23Ba2Cu3O7−δ is investigated. It has been established that the excess conductivity, Δσ(T), of these single crystals in a wide temperature range Tf < T < T* can be described by an exponential temperature dependence. The description of the excess conductivity using the relation Δσ ~ (1 − T/T*)exp(Δ*ab/T) can be interpreted in terms of the mean-field theory, where T* is represented as the temperature pseudogap opening, and the temperature dependence of the pseudogap (PG) is satisfactorily described in the framework of the BCS-BEC crossover theory. An increase in the applied pressure leads to the effect of narrowing the temperature interval for the realization of the PG-regime, thereby expanding the region of the linear dependence ρ(T) in the ab-plane.

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