Effects of Localized Holes on Charge Transport, Local Structure and Spin Dynamics in the Metallic State of CMR La1-xCaxMnO3

1997 ◽  
Vol 494 ◽  
Author(s):  
R. H. Heffner ◽  
M. F. Hundley ◽  
C. H. Booth
Keyword(s):  
Degrees Of Freedom ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Functional Dependence ◽  
Spatial Inhomogeneity ◽  
Metallic State ◽  
Colossal Magnetoresistive ◽  
Spatially Inhomogeneous ◽  
Inhomogeneous Spin ◽  
X Ray Absorption

ABSTRACTWe review resistivity, x-ray-absorption fine-structure (XAFS) and muon spin relaxation (μSR) data which provide clear evidence for localized holes causing polaron distortion and unusual spin dynamics below Tc in “colossal magnetoresistive” (CMR) La1-xCaxMnO3. Resistivity measurements for x=0.33 under an applied field H have shown that ln[ρ(H,T)] α -M, where M is the magnetization. The XAFS data show a similar functional dependence for the polaron distortions on M. The data from these two measurements are interpreted in terms of some fraction of the available holes x remaining localized and some increasing fraction becoming delocalized with increasing M. Finally, this polaron-induced spatial inhomogeneity yields anomalously slow, spatially inhomogeneous spin dynamics below Tc, as shown in the μSR data. These experiments individually probe the charge, lattice and spin degrees of freedom in this CMR system and suggest that the polarons retain some identity even at temperatures significantly below Tc.

scholarly journals Development of short and long-range magnetic order in the double perovskite based frustrated triangular lattice antiferromagnet Ba$$_{2}$$MnTeO$$_{6}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Khatua ◽  
T. Arh ◽  
Shashi B. Mishra ◽  
H. Luetkens ◽  
A. Zorko ◽  
...  
Keyword(s):  
Triangular Lattice ◽  
Degrees Of Freedom ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Magnetic Ordering ◽  
Double Exchange ◽  
Double Perovskite ◽  
Magnetic Interactions ◽  
Spin Frustration ◽  
Ordered State

AbstractFrustrated magnets based on oxide double perovskites offer a viable ground wherein competing magnetic interactions, macroscopic ground state degeneracy and complex interplay between emergent degrees of freedom can lead to correlated quantum phenomena with exotic excitations highly relevant for potential technological applications. By local-probe muon spin relaxation ($$\mu$$ μ SR) and complementary thermodynamic measurements accompanied by first-principles calculations, we here demonstrate novel electronic structure and magnetic phases of Ba$$_{2}$$ 2 MnTeO$$_{6}$$ 6 , where Mn$$^{2+}$$ 2 + ions with S = 5/2 spins constitute a perfect triangular lattice. Magnetization results evidence the presence of strong antiferromagnetic interactions between Mn$$^{2+}$$ 2 + spins and a phase transition at $$T_{N}$$ T N = 20 K. Below $$T_{N}$$ T N , the specific heat data show antiferromagnetic magnon excitations with a gap of 1.4 K, which is due to magnetic anisotropy. $$\mu$$ μ SR reveals the presence of static internal fields in the ordered state and short-range spin correlations high above $$T_{N}$$ T N . It further unveils critical slowing-down of spin dynamics at $$T_{N}$$ T N and the persistence of spin dynamics even in the magnetically ordered state. Theoretical studies infer that Heisenberg interactions govern the inter- and intra-layer spin-frustration in this compound. Our results establish that the combined effect of a weak third-nearest-neighbour ferromagnetic inter-layer interaction (owing to double-exchange) and intra-layer interactions stabilizes a three-dimensional magnetic ordering in this frustrated magnet.

Spin Dynamics in Antiferromagnets with Domain Walls and Disclinations

2020 ◽  
Vol 65 (10) ◽  
pp. 924
Author(s):  
E. G. Galkina ◽  
V. E. Kireev ◽  
R. V. Ovcharov ◽  
R. S. Khymyn ◽  
B. A. Ivanov
Keyword(s):  
Model Equation ◽  
Sigma Model ◽  
Domain Walls ◽  
Spin Dynamics ◽  
Spin Current ◽  
Spin Precession ◽  
Excitation Threshold ◽  
Internal Dynamics ◽  
Spatially Inhomogeneous ◽  
Inhomogeneous Spin

The spin dynamics in antiferromagnets with atomic dislocations and dislocation-induced spin disclinations has been discussed. It is shown how the usual sigma-model equation can be used to describe it. The dynamical states with the spatially inhomogeneous spin precession are studied. It is demonstrated that such an internal dynamics of the spin disclinations and the related domain walls can serve as a basis for creating a spin-Hall nanogenerator pumped with a spin current and characterized by a low excitation threshold.

Spin dynamics in the organic spin - Peierls system MEM(TCNQ) studied using muon-spin relaxation

1997 ◽  
Vol 9 (9) ◽  
pp. L119-L124 ◽  
Author(s):  
S J Blundell ◽  
F L Pratt ◽  
P A Pattenden ◽  
M Kurmoo ◽  
K H Chow ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Muon Spin Relaxation

scholarly journals Dichotomy in temporal and thermal spin correlations observed in the breathing pyrochlore LiGa1−xInxCr4O8

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Lee ◽  
S.-H. Do ◽  
W. Lee ◽  
Y. S. Choi ◽  
J. van Tol ◽  
...  
Keyword(s):  
Time Scale ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Quantum Spin ◽  
Spin Liquid ◽  
Fast Time ◽  
Spin Liquids ◽  
Magnetic Ground State ◽  
Spin Correlations ◽  
Magnetic Specific Heat

AbstractA breathing pyrochlore system is predicted to host a variety of quantum spin liquids. Despite tremendous experimental and theoretical efforts, such sought-after states remain elusive as perturbation terms and lattice distortions lead to magnetic order. Here, we utilize bond alternation and disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore LiGa1−xInxCr4O8. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in x = 0.8, namely, a nearly T2-dependent magnetic specific heat and persistent spin dynamics by muon spin relaxation (μSR). Moreover, 7Li NMR, ZF-μSR, and ESR unveil the temporal and thermal dichotomy of spin correlations: a tetramer singlet on a slow time scale vs. a spin-liquid-like state on a fast time scale. Our results showcase that a bond disorder in the breathing pyrochlore offers a promising route to disclose exotic magnetic phases.

Muon-spin-relaxation investigation of the spin dynamics of geometrically frustrated chromium spinels

2002 ◽  
Vol 66 (17) ◽  
Author(s):  
M. T. Rovers ◽  
P. P. Kyriakou ◽  
H. A. Dabkowska ◽  
G. M. Luke ◽  
M. I. Larkin ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Muon Spin Relaxation ◽  
Geometrically Frustrated

scholarly journals Crystal-Field Mediated Electronic Transitions of EuS up to 35 GPa

2021 ◽  
Author(s):  
Virginia Monteseguro ◽  
Jose Antonio Barreda-Argüeso ◽  
Javier Ruiz-Fuertes ◽  
Angelika Rosa ◽  
Holger L. Meyerheim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Crystal Field ◽  
Local Structure ◽  
Electronic Transitions ◽  
Metallic State ◽  
X Ray ◽  
Half Metal ◽  
Consistent Model ◽  
X Ray Absorption ◽  
Pressure Evolution

Abstract An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu2+ in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the 4f75d0 → 4f65d1 electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state.

Low temperature spin dynamics of geometrically frustrated antiferromagnets Y2Mo2O7 and Y2Mo1.6Ti0.4O7 studied by muon spin relaxation

1996 ◽  
Vol 79 (8) ◽  
pp. 6636 ◽  
Author(s):  
S. R. Dunsiger ◽  
R. F. Kiefl ◽  
K. H. Chow ◽  
B. D. Gaulin ◽  
M. J. P. Gingras ◽  
...  
Keyword(s):  
Low Temperature ◽  
Spin Relaxation ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Muon Spin Relaxation ◽  
Geometrically Frustrated
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