NEGATIVE MAGNETORESISTANCE BEHAVIOURS AND LOCALIZED MAGNETIC MOMENTS IN INSULATING CdSe SEMICONDUCTOR AT VERY LOW TEMPERATURES WITH MAGNETIC FIELD

2010 ◽  
Author(s):  
A. El kaaouachi ◽  
R. Abdia ◽  
A. Nafidi ◽  
A. Zatni ◽  
H. Sahsah ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Magnetic Moments ◽  
Negative Magnetoresistance

HIGH-FIELD TRANSPORT PROPERTIES OF T'-Ln2-xCexCuO4 (Ln=Nd, Pr, La)

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3216-3219 ◽  
Author(s):  
T. SEKITANI ◽  
N. MIURA ◽  
M. NAITO
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Transport Properties ◽  
Normal State ◽  
Low Temperatures ◽  
High Field ◽  
Magnetic Moments ◽  
Negative Magnetoresistance ◽  
High Magnetic Fields

We report low-temperature magnetotransport in the normal state of the electron-doped superconductors, Nd 2-x Ce x CuO 4, Pr 2-x Ce x CuO 4, and La 2-x Ce x CuO 4, by suppressing the superconductivity with high magnetic fields. The normal state ρ-T curve shows an up-turn at low temperatures, which has a log T dependence with saturation at lowest temperatures. The up-turn is gradually suppressed with increasing magnetic field, resulting in negative magnetoresistance. We discuss these findings on the basis of the Kondo scattering originating from the magnetic moments of Cu 2+ ions.

scholarly journals Elastocaloric-effect-induced adiabatic magnetization in paramagnetic salts due to the mutual interactions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lucas Squillante ◽  
Isys F. Mello ◽  
Antonio C. Seridonio ◽  
Mariano de Souza
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Body Problem ◽  
Magnetic Moments ◽  
Many Body ◽  
Elastocaloric Effect ◽  
Subtle Effect ◽  
Magnetic Insulators ◽  
Bose Einstein ◽  
Adiabatic Magnetization

AbstractThe temperature change under adiabatic stress, i.e., the elastocaloric effect, is a well-understood phenomenon and of particular interest due to its potential application in alternative ways for refrigeration. Here, we demonstrate that in the regime of low-temperatures (a few mK) real paramagnets can be magnetized when compressed adiabatically without applied magnetic field. Such adiabatic magnetization is a genuine many-body problem, stemming from the inherent dipolar mutual interactions between adjacent magnetic moments. We showcase experimental setups to carry out adiabatic magnetization and thus to access such a subtle effect. Perspectives of further investigations by controlling the mutual interactions in Bose–Einstein condensates in magnetic insulators and dipolar spin-ice systems via the adiabatic increase of temperature are also presented. Yet, we discuss the connection between the elastic Grüneisen parameter and the shift on the critical temperature of second-order phase transitions under adiabatic stress, as well as its connection with the Ehrenfest relation.

TEMPERATURE AND FIELD DEPENDENT MÖSSBAUER STUDY OF CeSn3andCeSn3.1 CRYSTALS

2009 ◽  
Vol 23 (02) ◽  
pp. 265-273
Author(s):  
R. K. SINGHAL ◽  
D. R. SÁNCHEZ ◽  
ELISA SAITOVITCH ◽  
S. K. GAUR ◽  
K. B. GARG
Keyword(s):  
Magnetic Field ◽  
Hyperfine Field ◽  
Low Temperatures ◽  
Room Temperature ◽  
Magnetic Moments ◽  
Mössbauer Study ◽  
Cubic Crystal ◽  
Temperature Range ◽  
Negative Results ◽  
The Magnetic Field

Mössbauer spectroscopic measurements have been carried out for CeSn 3 and CeSn 3.1 single crystals in the temperature range 1.5 K to 300 K under applied magnetic field, with an aim to look into the local surroundings of the Sn site and the possibility of magnetization at low temperatures. The spectra indicate a paramagnetic ground state throughout the temperature range with two different doublets associated with two sites S1 and S2. This indicates two crystallographic sites of Sn with the presence of a distortion in the cubic crystal. However, the contribution of S2 site is very small (only 3% for the CeSn 3 but slightly higher, i.e., 4.3% for the CeSn 3.1) at room temperature. Upon cooling (below 4 K), the S2 contribution disappears for the stoichiometric sample ( CeSn 3) but continues to stay for the slightly nonstoichiometric compound ( CeSn 3.1). The isomer shift reveals a Sn 2+ valence state throughout. A weak hyperfine field has been observed only at low temperatures (4.2 and 1.5 K spectra) for both the compounds, but not for the 300 K spectra. This is indicative of some magnetization, i.e., an increase in magnetic moments of Ce atoms, that is felt by the neighbor Sn atoms through RKKY interactions. However, upon cooling the samples from 4.2 K to 1.5 K, no further enhancement in magnetization is observed. The magnetic field was also applied for the CeSn 3 sample at low temperatures to check if there is any enhancement in the magnetic properties that yielded negative results, i.e., the applied field is equal to the hyperfine field, indicating no enhancement of magnetic moment.

MAGNETIC FIELD DEPENDENT RELAXATION TIME IN p-InSb AT LOW TEMPERATURES

1981 ◽  
Vol 42 (C5) ◽  
pp. C5-689-C5-693
Author(s):  
J. D.N. Cheeke ◽  
G. Madore ◽  
A. Hikata
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Low Temperatures ◽  
Field Dependent

Negative magnetoresistance in insulating CdSe and localized magnetic moments

2008 ◽  
Vol 33 (4) ◽  
pp. 351-356
Author(s):  
Rachid Abdia ◽  
Ablehamid El Kaaouachi ◽  
Abdelhakim Nafidi ◽  
Gérard Biskupski ◽  
Jamal Hemine
Keyword(s):  
Magnetic Moments ◽  
Negative Magnetoresistance

Simple Systems

2017 ◽  
Author(s):  
Jochen Rau
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
General Framework ◽  
Gibbs State ◽  
Macroscopic System ◽  
Basic Model ◽  
System A ◽  
Paramagnetic Salt ◽  
High And Low Temperatures ◽  
Simple Systems

Even though the general framework of statistical mechanics is ultimately targeted at the description of macroscopic systems, it is illustrative to apply it first to some simple systems: a harmonic oscillator, a rotor, and a spin in a magnetic field. These applications serve to illustrate how a key function associated with the Gibbs state, the so-called partition function, is calculated in practice, how the entropy function is obtained via a Legendre transformation, and how such systems behave in the limits of high and low temperatures. After discussing these simple systems, this chapter considers a first example where multiple constituents are assembled into a macroscopic system: a basic model of a paramagnetic salt. It also investigates the size of energy fluctuations and how—in the case of the paramagnet—these fluctuations scale with the number of constituents.

scholarly journals Review of Multi-Physics Modeling on the Active Magnetic Regenerative Refrigeration

2021 ◽  
Vol 26 (2) ◽  
pp. 47
Author(s):  
Julien Eustache ◽  
Antony Plait ◽  
Frédéric Dubas ◽  
Raynal Glises
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Room Temperature ◽  
State Of The Art ◽  
Vapor Compression ◽  
Crucial Step ◽  
Potential Alternative ◽  
Vapor Compression Refrigeration ◽  
Preliminary Study ◽  
Physics Modeling

Compared to conventional vapor-compression refrigeration systems, magnetic refrigeration is a promising and potential alternative technology. The magnetocaloric effect (MCE) is used to produce heat and cold sources through a magnetocaloric material (MCM). The material is submitted to a magnetic field with active magnetic regenerative refrigeration (AMRR) cycles. Initially, this effect was widely used for cryogenic applications to achieve very low temperatures. However, this technology must be improved to replace vapor-compression devices operating around room temperature. Therefore, over the last 30 years, a lot of studies have been done to obtain more efficient devices. Thus, the modeling is a crucial step to perform a preliminary study and optimization. In this paper, after a large introduction on MCE research, a state-of-the-art of multi-physics modeling on the AMRR cycle modeling is made. To end this paper, a suggestion of innovative and advanced modeling solutions to study magnetocaloric regenerator is described.

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