scholarly journals Colossal Magnetoresistance in a Mott Insulator via Magnetic Field-Driven Insulator-Metal Transition

2016 ◽  
Vol 116 (21) ◽  
Author(s):  
M. Zhu ◽  
J. Peng ◽  
T. Zou ◽  
K. Prokes ◽  
S. D. Mahanti ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Mott Insulator ◽  
Insulator Metal Transition

scholarly journals Low-temperature dielectric anomaly arising from electronic phase separation at the Mott insulator-metal transition

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
A. Pustogow ◽  
R. Rösslhuber ◽  
Y. Tan ◽  
E. Uykur ◽  
A. Böhme ◽  
...  
Keyword(s):  
Phase Separation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Coulomb Repulsion ◽  
Mott Insulator ◽  
Electronic Phase Separation ◽  
First Order Phase Transition ◽  
Electronic Phase ◽  
Insulator Metal Transition ◽  
First Order Phase

AbstractCoulomb repulsion among conduction electrons in solids hinders their motion and leads to a rise in resistivity. A regime of electronic phase separation is expected at the first-order phase transition between a correlated metal and a paramagnetic Mott insulator, but remains unexplored experimentally as well as theoretically nearby T = 0. We approach this issue by assessing the complex permittivity via dielectric spectroscopy, which provides vivid mapping of the Mott transition and deep insight into its microscopic nature. Our experiments utilizing both physical pressure and chemical substitution consistently reveal a strong enhancement of the quasi-static dielectric constant ε1 when correlations are tuned through the critical value. All experimental trends are captured by dynamical mean-field theory of the single-band Hubbard model supplemented by percolation theory. Our findings suggest a similar ’dielectric catastrophe’ in many other correlated materials and explain previous observations that were assigned to multiferroicity or ferroelectricity.

scholarly journals Описание колоссального магнитосопротивления La-=SUB=-1.2-=/SUB=-Sr-=SUB=-1.8-=/SUB=-Mn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- на основе "спин-поляронного" и "ориентационного" механизмов проводимости в парамагнитной области температур

2020 ◽  
Vol 62 (5) ◽  
pp. 669
Author(s):  
С.А. Гудин ◽  
Н.И. Солин
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Main Role ◽  
Spin Polaron ◽  
Temperature Range ◽  
Conduction Mechanisms ◽  
Theoretical Investigations ◽  
Temperature Dependences ◽  
The Magnetic Field ◽  
Good Agreement

Experimental and theoretical investigations of the resistance of the La1.2Sr1.8Mn2O7 single crystal in magnetic fields from 0 to 90 kOe and in the temperature range from 75 to 300 K has been studied. The magnetoresistance is determined by the “spin-polaron” and “orientation” conduction mechanisms. Using the method of separating contributions to the magnetoresistance from several conduction mechanisms, the observed magnetoresistance of La1.2Sr1.8Mn2O7 manganite in the temperature range of 75-300 K is described, good agreement between the calculated and experimental data is obtained. In a magnetic field of 0 and 90 kOe, the temperature dependences of the size of the spin polaron (in relative units) are calculated for the temperature range 75–300 K. It is shown, that the КМС value is determined by an increase in the linear size of the spin polaron (along the magnetic field), i.e. the main role in the magnitude of the colossal magnetoresistance is made by the change in the size of the magnetic inhomogeneities of the crystal.

scholarly journals Theory of Insulator Metal Transition and Colossal Magnetoresistance in Doped Manganites

2004 ◽  
Vol 92 (15) ◽  
Author(s):  
T. V. Ramakrishnan ◽  
H. R. Krishnamurthy ◽  
S. R. Hassan ◽  
G. Venketeswara Pai
Keyword(s):  
Colossal Magnetoresistance ◽  
Insulator Metal Transition ◽  
Doped Manganites

scholarly journals Magnetic Field Measurements during Magnetic Pulse Welding Using CMR-B-Scalar Sensors

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5925
Author(s):  
Voitech Stankevic ◽  
Joern Lueg-Althoff ◽  
Marlon Hahn ◽  
A. Erman Tekkaya ◽  
Nerija Zurauskiene ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Welding Process ◽  
Nondestructive Method ◽  
Magnetic Field Measurement ◽  
Magnetic Pulse ◽  
Magnetic Pulse Welding ◽  
Pulse Welding ◽  
The Magnetic Field

The possibility of applying CMR-B-scalar sensors made from thin manganite films exhibiting the colossal magnetoresistance effect as a fast-nondestructive method for the evaluation of the quality of the magnetic pulse welding (MPW) process is investigated in this paper. This method based on magnetic field magnitude measurements in the vicinity of the tools and joining parts was tested during the electromagnetic compression and MPW of an aluminum flyer tube with a steel parent. The testing setup used for the investigation allowed the simultaneous measurement of the flyer displacement, its velocity, and the magnitude of the magnetic field close to the flyer. The experimental results and simulations showed that, during the welding of the aluminum tube with the steel parent, the maximum magnetic field in the gap between the field shaper and the flyer is achieved much earlier than the maximum of the current pulse of the coil and that the first half-wave pulse of the magnetic field has two peaks. It was also found that the time instant of the minimum between these peaks depends on the charging energy of the capacitors and is associated with the collision of the flyer with the parent. Together with the first peak maximum and its time-position, this characteristic could be an indication of the welding quality. These results were confirmed by simultaneous measurements of the flyer displacement and velocity, as well as a numerical simulation of the magnetic field dynamics. The relationship between the peculiarities of the magnetic field pulse and the quality of the welding process is discussed. It was demonstrated that the proposed method of magnetic field measurement during magnetic pulse welding in combination with subsequent peel testing could be used as a nondestructive method for the monitoring of the quality of the welding process.

Evidence for a Universal Relationship Between Magnetization and Changes in the Local Structure

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3726-3728 ◽  
Author(s):  
L. Downward ◽  
F. Bridges ◽  
D. Cao ◽  
J. Neumeier ◽  
L. Zhou
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Local Structure ◽  
Pair Distribution Function ◽  
Colossal Magnetoresistance ◽  
X Ray ◽  
Polaron State ◽  
Universal Relationship ◽  
High Fields ◽  
X Ray Absorption

X-ray Absorption Fine Structure (XAFS) measurements of the colossal magnetoresistance (CMR) sample La 0.79 Ca 0.21 MnO 3 at high fields indicate a decrease in the width parameter of the pair distribution function, σ, as the applied magnetic field is increased for T near Tc. The change in σ2 from the disordered polaron state varies approximately exponentially with magnetization irrespective of whether the sample magnetization was achieved through a change in temperature or the application of an external magnetic field. This suggests a more universal relationship between local structure and the sample magnetization than was previously indicated.

Pressure-induced Mott-insulator–metal crossover at ambient temperature in an overexpanded fulleride

2018 ◽  
Vol 2 (5) ◽  
pp. 993-998 ◽  
Author(s):  
Ruth H. Zadik ◽  
Yasuhiro Takabayashi ◽  
Ross H. Colman ◽  
Gaston Garbarino ◽  
Kosmas Prassides
Keyword(s):  
Ambient Temperature ◽  
Mott Insulator ◽  
External Pressure ◽  
Insulator Metal Transition

The Mott-insulator–metal transition in A3C60 fullerides is traversed at ambient temperature through the application of external pressure.

MONTE CARLO STUDY OF ONE HOLE IN A QUANTUM ANTIFERROMAGNET

1992 ◽  
Vol 06 (05n06) ◽  
pp. 587-588
Author(s):  
S. Sorella
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Thermodynamic Limit ◽  
Quantum Monte Carlo ◽  
Finite Size ◽  
Monte Carlo Study ◽  
Mott Insulator ◽  
Trial Wavefunction ◽  
The One ◽  
Quantum Antiferromagnet

Using the standard Quantum Monte Carlo technique for the Hubbard model, I present here a numerical investigation of the hole propagation in a Quantum Antiferromagnet. The calculation is very well stabilized, using selected sized systems and special use of the trial wavefunction that satisfy the “close shell condition” in presence of an arbitrarily weak Zeeman magnetic field, vanishing in the thermodynamic limit. It will be shown in a forthcoming publication1 that the presence of this magnetic field does not affect thermodynamic properties for the half filled system. Then I have used the same selected sizes for the one hole ground state. I have investigated the question of vanishing or nonvanishing quasiparticle weight, in order to clarify whether the Mott insulator should behave just as conventional insulator with an upper and lower Hubbard band. By comparing the present finite size scaling with several techniques predicting a finite quasiparticle weight (see Fig.1) the data seem more consistent with a vanishing quasiparticle weight, i.e. , as recently suggested by P.W. Anderson2 the Hubbard-Mott insulator should be characterized by non-trivial excitations which cannot be interpreted in a simple quasi-particle picture. However it cannot be excluded , based only on numerical grounds, that a very small but non vanishing quasiparticle weight should survive in the thermodynamic limit.

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