scholarly journals Phase Separation and Phase Diagram in Lightly Doped Manganites: Temperature and Magnetic Field Effects

1999 ◽  
Vol 52 (2) ◽  
pp. 247 ◽  
Author(s):  
Liang-Jian Zou ◽  
H. Q. Lin
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Phase Separation ◽  
Doping Concentration ◽  
Double Exchange ◽  
Magnetic Field Effects ◽  
Jahn Teller ◽  
Doped Manganites ◽  
And Shifts ◽  
Canted Phase

The effects of magnetic field and temperature on the phase separation and phase diagram of lightly doped manganites are studied. Based on the double exchange model with on-site Coulomb interaction, we show that in the case of a homogeneous charge distribution, the canting angle of localised core spins and the critical doping concentration of the system from canted phase to ferromagnetic (FM) phase become large because the effective FM coupling between localised core spins is weakened when the temperature increases. The boundary of the canted phase and FM phase shifts to a high doping concentration regime at high temperatures. In comparison with with the zero-temperature result, the phase separation can take place more easily in lightly doped manganites at finite temperatures. The application of a magnetic field decreases the energy of the FM cluster in the system, favours the separation of the hole-rich FM phase from the antiferromagnetic (AFM) background, and shifts the cant-FM border to the low doping regime. The effect of the Jahn-Teller electron-phonon coupling on the phase diagram and phase separation is also discussed.

Phase Separation in Models for Manganites

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3369-3371
Author(s):  
Adriana Moreo
Keyword(s):  
Phase Diagram ◽  
Phase Separation ◽  
Low Temperature ◽  
Parameter Space ◽  
Double Exchange ◽  
Computational Techniques ◽  
Low Density ◽  
Spin Correlations ◽  
Jahn Teller ◽  
Antiferromagnetic Domains

Using computational techniques the phase diagram of models for manganites is studied. In the absence of Jahn–Teller phonons three regimes are found to dominate the low temperature properties of these models: (i) a ferromagnetic region induced by the double-exchange mechanism; (ii) a region with incommensurate spin correlations at small Hund coupling; and (iii) a novel regime of phase separation (PS) between hole-rich ferromagnetic and hole-poor antiferromagnetic domains. PS occurs both at high- and low density of eg electrons. Experiments for manganites compatible with the presence of PS are discussed. In the presence of dynamical Jahn–Teller phonons, PS is also observed and, in addition, staggered orbital order exists in some regions of parameter space.

FRACTAL AND DYNAMICAL PROPERTIES OF THE KICKED HARPER MODEL

1994 ◽  
Vol 08 (03) ◽  
pp. 207-235 ◽  
Author(s):  
R. ARTUSO ◽  
G. CASATI ◽  
F. BORGONOVI ◽  
L. REBUZZINI ◽  
I. GUARNERI
Keyword(s):  
Magnetic Field ◽  
State Physics ◽  
Phase Diagram ◽  
Quantum Chaos ◽  
Multifractal Analysis ◽  
Model System ◽  
Magnetic Field Effects ◽  
Solid State Physics ◽  
Rich Phase ◽  
Dynamical Properties

We review recent work on the so-called kicked Harper model, which can be viewed either as a model system in the framework of quantum chaos, or as a pulsed version of the Harper model, which has been thoroughly investigated in the context of magnetic field effects in solid state physics. In particular we describe its rich phase diagram, by means of both dynamical methods and multifractal analysis of the spectrum.

Magnetic-field effects on Jahn-Teller distortion in ferroelastic magnetic insulator Fe1−xMnxCr2O4

2011 ◽  
Vol 99 (8) ◽  
pp. 082506 ◽  
Author(s):  
H. Sagayama ◽  
S. Ohtani ◽  
M. Saito ◽  
N. Abe ◽  
K. Taniguchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Field Effects ◽  
Teller Distortion ◽  
Field Effects ◽  
Jahn Teller ◽  
Magnetic Insulator ◽  
Jahn Teller Distortion

Phase separation in La–Ca manganites: Magnetic field effects

2008 ◽  
Vol 320 (3-4) ◽  
pp. 523-527 ◽  
Author(s):  
M. Tovar ◽  
M.T. Causa ◽  
C.A. Ramos ◽  
D. Laura-Ccahuana
Keyword(s):  
Magnetic Field ◽  
Phase Separation ◽  
Magnetic Field Effects ◽  
Field Effects

scholarly journals High magnetic field phase diagram in electron-doped manganites La0.4Ca0.6Mn1−yCryO3

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Chengliang Lu ◽  
Ni Hu ◽  
Ming Yang ◽  
Shuangcheng Xia ◽  
Haowen Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
High Magnetic Field ◽  
Field Phase ◽  
Doped Manganites

scholarly journals Striping of orbital-order with charge-disorder in optimally doped manganites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei-Tin Chen ◽  
Chin-Wei Wang ◽  
Ching-Chia Cheng ◽  
Yu-Chun Chuang ◽  
Arkadiy Simonov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Doping Level ◽  
Colossal Magnetoresistance ◽  
Phase Segregation ◽  
Crystallographic Analysis ◽  
Prototype System ◽  
Jahn Teller ◽  
Doped Manganites ◽  
Natural Mechanism ◽  
Lattice Modes

AbstractThe phase diagrams of LaMnO3 perovskites have been intensely studied due to the colossal magnetoresistance (CMR) exhibited by compositions around the $${\frac{3}{8}}^{th}$$ 3 8 t h doping level. However, phase segregation between ferromagnetic (FM) metallic and antiferromagnetic (AFM) insulating states, which itself is believed to be responsible for the colossal change in resistance under applied magnetic field, has prevented an atomistic-level understanding of the orbital ordered (OO) state at this doping level. Here, through the detailed crystallographic analysis of the phase diagram of a prototype system (AMn$${}_{3}^{A^{\prime} }$$ 3 A ′ Mn$${}_{4}^{B}$$ 4 B O12), we show that the superposition of two distinct lattice modes gives rise to a striping of OO Jahn-Teller active Mn3+ and charge disordered (CD) Mn3.5+ layers in a 1:3 ratio. This superposition only gives a cancellation of the Jahn-Teller-like displacements at the critical doping level. This striping of CD Mn3.5+ with Mn3+ provides a natural mechanism though which long range OO can melt, giving way to a conducting state.

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