Charge ordering and magnetoresistance inNd1−xCaxMnO3due to reduced double exchange

1996 ◽  
Vol 54 (5) ◽  
pp. 3007-3010 ◽  
Author(s):  
K. Liu ◽  
X. W. Wu ◽  
K. H. Ahn ◽  
T. Sulchek ◽  
C. L. Chien ◽  
...  
Keyword(s):  
Double Exchange ◽  
Charge Ordering

Competition between the double exchange and charge ordering interactions in the bandwidth controlled (La,Nd)0.8Na0.2MnO3 manganites

2004 ◽  
Vol 351 (1-2) ◽  
pp. 114-120 ◽  
Author(s):  
Z.Q Li ◽  
H Liu ◽  
X.D Liu ◽  
P Wu ◽  
H.L Bai ◽  
...  
Keyword(s):  
Double Exchange ◽  
Charge Ordering

Effect of Cr Substitution on the Crystal and Magnetic Structure of (Pr0.55Ca0.45)MnO3

2006 ◽  
Vol 52 ◽  
pp. 93-97
Author(s):  
A. Martinelli ◽  
M. Ferretti ◽  
Carlo Castellano ◽  
M.R. Cimberle ◽  
M. Tropeano ◽  
...  
Keyword(s):  
Phase Transition ◽  
Monoclinic Phase ◽  
Magnetic Measurements ◽  
Double Exchange ◽  
Charge Ordering ◽  
Orbital Ordering ◽  
Magnetic Structures ◽  
Spin Ordering ◽  
Cr Substitution ◽  
Lower Temperature

The crystal and magnetic structures of (Pr0.55Ca0.45)(Mn1-yCry)O3 (y = 0.00, 0.03, 0.06) have been investigated between 5 and 300 K by means of neutron powder diffraction followed by Rietveld refinement and dc magnetic measurements. An orthorhombic-to-monoclinic phase transition occurs on cooling in (Pr0.55Ca0.45)MnO3; at lower temperature charge ordering in the Mn sub-lattice, coupled with orbital ordering, induces an anti-ferromagnetic (AFM) spin ordering within the monoclinic phase. Cr substitution at the Mn site hinders the phase transition, although for the y = 0.03 sample small amounts of the monoclinic phase co-exist at low temperature with the main phase characterized by an orthorhombic structure. In addition Cr favours ferromagnetism (FM) participating to the double exchange mechanism. Cr substitution prevents charge ordering, favouring double exchange and hence FM spin ordering within the Mn sub-lattice. The Curie temperature of the Cr substituted samples is independent on the Cr content.

scholarly journals Structural and Magnetic Properties of Nanosized Half-Doped Rare-Earth Ho0.5Ca0.5MnO3 Manganite

2022 ◽  
Vol 12 (2) ◽  
pp. 695
Author(s):  
Alessandra Geddo Lehmann ◽  
Giuseppe Muscas ◽  
Maurizio Ferretti ◽  
Emanuela Pusceddu ◽  
Davide Peddis ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Temperature Dependence ◽  
Sol Gel ◽  
Double Exchange ◽  
Exchange Interactions ◽  
Charge Ordering ◽  
Lattice Parameters ◽  
Orthorhombic Symmetry ◽  
Orbital Ordering ◽  
Structural And Magnetic Properties

We investigated the structural and magnetic properties of 20 nm-sized nanoparticles of the half-doped manganite Ho0.5Ca0.5MnO3 prepared by sol-gel approach. Neutron powder diffraction patterns show Pbnm orthorhombic symmetry for 10 K < T < 290 K, with lattice parameters a, b, and c in the relationship c/√2 < a < b, indicating a cooperative Jahn–Teller effect, i.e., orbital ordering OO, from below room temperature. In contrast with the bulk samples, in the interval 250 < T < 300 K, the fingerprint of charge ordering (CO) does not manifest itself in the temperature dependence of lattice parameters. However, there are signs of CO in the temperature dependence of magnetization. Accordingly, below 100 K superlattice magnetic Bragg reflections arise, which are consistent with an antiferromagnetic phase strictly related to the bulk Mn ordering of a charge exchange-type (CE-type), but characterized by an increased fraction of ferromagnetic couplings between manganese species themselves. Our results show that in this narrow band half-doped manganite, size reduction only modifies the balance between the Anderson superexchange and Zener double exchange interactions, without destabilizing an overall very robust antiferromagnetic state.

Atomic Scale Studies of La/Sr Ordering in Colossal Magnetoresistant La2−2xSr1+2xMn2O7 Single Crystals

2014 ◽  
Vol 20 (6) ◽  
pp. 1791-1797 ◽  
Author(s):  
Manuel A. Roldan ◽  
Mark P. Oxley ◽  
Qing’an Li ◽  
Hong Zheng ◽  
K. E. Gray ◽  
...  
Keyword(s):  
Single Crystals ◽  
Double Exchange ◽  
Significant Degree ◽  
Real Space ◽  
Charge Ordering ◽  
Atomic Scale ◽  
Orbital Ordering ◽  
Chemical Ordering ◽  
Electronic Phase ◽  
Image Simulations

AbstractTo date, it is unclear whether chemical order (or disorder) is in any way connected to double exchange, electronic phase separation, or charge ordering (CO) in manganites. In this work, we carry out an atomic resolution study of the colossal magnetoresistant manganite La2−2xSr1+2xMn2O7 (LSMO). We combine aberration-corrected electron microscopy and spectroscopy with spectroscopic image simulations, to analyze cation ordering at the atomic scale in real space in a number of LSMO single crystals. We compare three different compositions within the phase diagram: a ferromagnetic metallic material (x=0.36), an insulating, antiferromagnetic charge ordered (AF-CO) compound (x=0.5), which also exhibits orbital ordering, and an additional AF sample (x=0.56). Detailed image simulations are essential to accurately quantify the degree of chemical ordering of these samples. We find a significant degree of long-range chemical ordering in all cases, which increases in the AF-CO range. However, the degree of ordering is never complete nor can it explain the strongly correlated underlying ordering phenomena. Our results show that chemical ordering over distinct crystallographic sites is not needed for electronic ordering phenomena to appear in manganites, and cannot by itself explain the complex electronic behavior of LSMO.

scholarly journals From double exchange to superexchange in charge ordering perovskite manganites

1998 ◽  
Author(s):  
W. Bao ◽  
J.D. Axe ◽  
C.H. Chen ◽  
S.W. Cheong ◽  
P. Schiffer ◽  
...  
Keyword(s):  
Double Exchange ◽  
Charge Ordering ◽  
Perovskite Manganites

scholarly journals Impact of Ag-Doped on the Ferromagnetic-Metallic Transition in Pr0.75Na0.25mno3 Manganites

2018 ◽  
Vol 7 (4.30) ◽  
pp. 68
Author(s):  
N Khairulzaman ◽  
N Ibrahim ◽  
S Shamsuddin
Keyword(s):  
Single Phase ◽  
Ac Susceptibility ◽  
Double Exchange ◽  
Xrd Analysis ◽  
Charge Ordering ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Jahn Teller ◽  
Jahn Teller Effect

Monovalent doped Pr0.75Na0.25-yAgyMnO3 (y = 0–0.10) manganite have been investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) as well as DC electrical resistivity and AC susceptibility measurement to clarify the influence of Ag- doped on charge ordering (CO) state. XRD analysis revealed all samples consists of essentially single phase and crystallized in an orthorhombic structure with space group Pnma. SEM images of Pr0.75Na0.25-yAgyMnO3 compound shows the successful substitution of Ag+ ions with the enhancement of the grains boundaries and sizes as well as the compaction of particles. On the other hand, resistivity and susceptibility measurements showed that the y = 0 sample exhibits insulating behavior and anti-ferromagnetic. Interestingly, the ferromagnetic-metallic transition was observed for y = 0.05 due to the revival of double-exchange (DE) mechanism as a result of weakening the Jahn-Teller effect which caused the CO state to be weakened. However, increasing of Ag-doped up to y = 0.10 induce back its transition into anti-ferromagnetic insulating behavior suggestively due to the weakening of DE mechanism.

scholarly journals From double exchange to superexchange in charge-ordering perovskite manganites

1997 ◽  
Vol 241-243 ◽  
pp. 418-420 ◽  
Author(s):  
Wei Bao ◽  
J.D Axe ◽  
C.H Chen ◽  
S.-W Cheong ◽  
P Schiffer ◽  
...  
Keyword(s):  
Double Exchange ◽  
Charge Ordering ◽  
Perovskite Manganites

SPIN AND ORBITAL PHYSICS IN MANGANITES

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2727-2745 ◽  
Author(s):  
R. Y. GU ◽  
Z. D. WANG
Keyword(s):  
Colossal Magnetoresistance ◽  
Lattice Distortion ◽  
Double Exchange ◽  
Charge Ordering ◽  
Perovskite Manganites ◽  
Electronic Correlation ◽  
Strong Electronic Correlation ◽  
Jahn Teller ◽  
Orbital Physics ◽  
Magnetic Orbital

The spin and orbital physics in perovskite manganites is briefly reviewed. Perovskite manganites are well known as the materials exhibiting colossal magnetoresistance (CMR), whose mechanism is based on the double exchange (DE) interaction, in which the electron hopping is connected with the spin configurations of the manganite ions. Recent intensive studies have shown that this DE framework must be subjected to the strong correlation between orbital degenerate electrons. On one hand, the orbital degeneracy itself leads to an anisotropic DE hopping being different from the conventional DE, which in turn may result in the anisotropy of the magnetic structure, such as the A-type or the C-type antiferromagnetism. On the other hand, the electronic correlation between these degenerate electrons plays an important role in determining the phases of the system. The correlation can come from both the on-site Coulomb interaction and the Jahn–Teller coupling between the lattice distortion and the electrons. The interplay of the DE mechanism and the strong electronic correlation leads to various magnetic, orbital and/or charge ordering as well as the phase separation.

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