A MONTE CARLO STUDY OF THE SPECIFIC HEAT OF DILUTED ANTIFERROMAGNETS

1999 ◽  
Vol 10 (01) ◽  
pp. 233-239
Author(s):  
M. STAATS ◽  
K. D. USADEL
Keyword(s):  
Phase Transition ◽  
Specific Heat ◽  
Three Dimensional ◽  
Monte Carlo Study ◽  
Paramagnetic State ◽  
Zero Field ◽  
Longe Range ◽  
Zero Field Cooling ◽  
Ordered State ◽  
Field Cooling

The three-dimensional diluted antiferromagnet in a magnetic field has a longe-range ordered state for sufficiently low temperatures and external fields. We study the irreversibilities at the phase transition from this state into the paramagnetic state at higher temperatures. Performing field cooling and zero field cooling simulation procedures we find a small irreversibility in the internal energy and the specific heat, although the behavior of the order parameter is irreversible and the phase transition is suppressed in the FC case. The specific heat shows a noncritical broad maximum above the transition temperature Tc. The results are compatible with recent experimental results obtained by Satooka et al., whereas our interpretation of the data is different.

scholarly journals Síntesis del superconductor YBa2Cu3O7- δ mediante sinterización por descarga luminiscente anormal

2017 ◽  
Vol 41 (158) ◽  
pp. 36
Author(s):  
Erika Yazmin Soto-Gómez ◽  
Armando Sarmiento-Santos ◽  
Carlos Arturo Parra-Vargas
Keyword(s):  
Zero Field ◽  
Zero Field Cooling ◽  
Field Cooling

En este trabajo se reporta la síntesis del superconductor YBa2Cu3O7-δ mediante el método no convencional de sinterización por plasma en el rango de descarga luminiscente anormal (DLA). Las muestras se sometieron a diferentes temperaturas y tiempos de sinterización. Como referencia se usó una muestra superconductora obtenida por el método convencional (horno resistivo). La caracterización estructural de estas muestras se hizo por difracción de rayos X y refinamiento con el método de Rietveld. El comportamiento superconductor se determinó mediante el análisis de las curvas de magnetización en función de la temperatura según los procedimientos experimentales de enfriado en campo magnético cero (zero field cooling, ZFC) y enfriado con campo magnético aplicado (field cooling, FC). Las muestras sinterizadas por DLA presentaron características estructurales (ortorrómbica Pmmm) y superconductoras con una temperatura crítica de Tc~ 92 K, similares a las obtenidas por el método convencional, pero con una significativa reducción en las temperaturas y tiempos, bajo un ambiente adecuado de presión en el proceso de sinterización. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

scholarly journals Influence of Crystallite Size on the Magnetic Order in Semiconducting ZnCr2Se4 Nanoparticles

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3947 ◽  
Author(s):  
Ewa Malicka ◽  
Małgorzata Karolus ◽  
Tadeusz Groń ◽  
Adrian Gudwański ◽  
Andrzej Ślebarski ◽  
...  
Keyword(s):  
Single Crystal ◽  
Specific Heat ◽  
Spin Glass ◽  
Crystallite Size ◽  
Magnetic Order ◽  
Ac Susceptibility ◽  
High Energy ◽  
Zero Field ◽  
Bulk Single Crystal ◽  
Field Cooling

Structural, electrical, magnetic, and specific heat measurements were carried out on ZnCr2Se4 single crystal and on nanocrystals obtained from the milling of this single crystal after 1, 3, and 5 h, whose crystallite sizes were 25.2, 2.5, and 2 nm, respectively. For this purpose, the high-energy ball-milling method was used. The above studies showed that all samples have a spinel structure, and are p-type semiconductors with less milling time and n-type with a higher one. In turn, the decrease in crystallite size caused a change in the magnetic order, from antiferromagnetic for bulk material and nanocrystals after 1 and 3 h of milling to spin-glass with the freezing temperature Tf = 20 K for the sample after 5 h of milling. The spin-glass behavior for this sample was derived from a broad peak of dc magnetic susceptibility, a splitting of the zero-field-cooling and field-cooling susceptibilities, and from the shift of Tf towards the higher frequency of the ac susceptibility curves. A spectacular result for this sample is also the lack of a peak on the specific heat curve, suggesting a disappearance of the structural transition that is observed for the bulk single crystal.

Phase Transition under Zero-Field Heating after Field Cooling in (1-x)Pb(In1/2Nb1/2)O3–xPbTiO3

2009 ◽  
Vol 48 (9) ◽  
pp. 09KF07 ◽  
Author(s):  
Makoto Iwata ◽  
Keita Kuroda ◽  
Yusuke Hasegawa ◽  
Rintaro Aoyagi ◽  
Masaki Maeda ◽  
...  
Keyword(s):  
Phase Transition ◽  
Zero Field ◽  
Field Cooling

Calorimetric properties of a superconducting anisotropic square: ZFC process

2020 ◽  
pp. 2150128
Author(s):  
C. A. Aguirre ◽  
Q. D. Martins ◽  
J. Barba-Ortega
Keyword(s):  
Specific Heat ◽  
Free Energy Density ◽  
Vortex State ◽  
Cooper Pairs ◽  
Zero Field ◽  
Cooling Process ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equations ◽  
Zero Field Cooling

We analyzed the role of the inclusion of anti-dots on the vortex state and some calorimetric properties of a mesoscopic superconducting square immersed in an external applied magnetic field. We calculated the magnetization, entropy, Gibbs free energy, density of Cooper pairs and specific heat for this system in a zero field cooling process, solving the time-dependent Ginzburg–Landau equations. We found that the critical temperature is non-dependent on the number of anti-dots and dependent slightly on the size of the defects. Oscillations in the entropy and specific heat are found due the temperature dependence of the superconducting characteristics length.

Induction technique for superconducting rings between field cooling and zero field cooling

2007 ◽  
Vol 459 (1-2) ◽  
pp. 24-26 ◽  
Author(s):  
H. González-Jorge ◽  
I. Quelle ◽  
L. Romaní ◽  
G. Domarco
Keyword(s):  
Zero Field ◽  
Induction Technique ◽  
Superconducting Rings ◽  
Zero Field Cooling ◽  
Field Cooling

Enhanced ferroelectricity and ferromagnetism in La1−xBixCrO3 by Bi3+ substitution

2007 ◽  
Vol 22 (8) ◽  
pp. 2081-2086 ◽  
Author(s):  
H-Y. Guo ◽  
J.I.L. Chen ◽  
Z-G. Ye ◽  
A.S. Arrott
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Quantum Interference ◽  
Remanent Polarization ◽  
Magnetic Hysteresis ◽  
Zero Field ◽  
Ferroelectric Hysteresis ◽  
Different Origins ◽  
Zero Field Cooling ◽  
Field Cooling

The ferroelectric and magnetic properties of the perovskite solid solution, (1 − x)LaCrO3–xBiCrO3, have been investigated. While pure LaCrO3 does not show ferroelectric hysteresis even at 77 K, the solid solution of La1−xBixCrO3 with x = 0.1, 0.2, 0.3, and 0.35 displays ferroelectric hysteresis, with the remanent polarization increasing with the increase of the Bi3+ content. Using a superconducting quantum interference device, the magnetization was measured versus temperature under field cooling (FC) and zero field cooling (ZFC) conditions. Magnetic hysteresis has been found in La1−xBixCrO3 (0.1 ⩽ x ⩽ 0.3) below the Néel temperature, TN. With the increase of Bi3+ content, TN decreases, while the magnetization below TN is enhanced. While the ferroelectric and magnetic properties could be due to different origins, the Bi substitution results in both ferroelectric and magnetic enhancements in the (1 − x)LaCrO3–xBiCrO3 solid solutions.

Calculation of the Interaction Forces between Superconductor and Permanent Magnet Using Equivalent Current Loops in Zero Field Cooling

2013 ◽  
Vol 634-638 ◽  
pp. 2436-2441
Author(s):  
Yong Yang ◽  
Xiao Jing Zheng ◽  
Tao Li ◽  
Zhi Qiang Hua
Keyword(s):  
Permanent Magnets ◽  
High Temperature Superconductors ◽  
Magnetic Bearing ◽  
Image Method ◽  
Zero Field ◽  
Vertical Force ◽  
Interaction Forces ◽  
Magnetic Dipoles ◽  
Zero Field Cooling ◽  
Field Cooling

The levitation between high temperature superconductors (HTSs) and permanent magnets (PMs) has been applied to the flywheel energy storage systems and magnetic bearing systems for the last nearly twenty years. The interaction forces acting on the levitating body are calculated by the modified frozen-image method. The magnetic dipoles are equivalent to Amperian current loops. The current intensity in loops changes linearly when the PM moves. Under the zero field cooling condition, the expression of vertical force is obtained when the PM traverses vertically, and when the PM traverses horizontally, the expressions of vertical and horizontal forces are obtained. Those expressions of vertical and horizontal forces are gained by calculating the forces between current loops and using superposition theorem of vector. The calculations agree well with the previous experimental data, which means that the deductions of the expressions are reliable.

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