Formation of the C-type Orbital-Ordered State in the Simple Perovskite Manganite Sr1-xSmxMnO3

MRS Advances ◽  
2016 ◽  
Vol 1 (9) ◽  
pp. 615-620 ◽  
Author(s):  
Misato Yamagata ◽  
Ayumi Shiratani ◽  
Yasuhide Inoue ◽  
Yasumasa Koyama
Keyword(s):  
Electronic System ◽  
The State ◽  
Tetragonal Symmetry ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Rotational Displacement ◽  
Type Orbital ◽  
Jahn Teller ◽  
Jahn Teller Distortion

ABSTRACTThe simple perovskite manganite Sr1-xSmxMnO3 (SSMO) has been reported to have a highly-correlated electronic system for eg-electrons in a Mn ion. According to the previous studies, the C-type orbital-ordered (COO) state with the I4/mcm symmetry was found to be formed from the disordered-cubic (DC) state on cooling. The feature of the COO state is that its crystal structure involves both the Jahn-Teller distortion to orbital ordering and the R25-type rotational displacement of oxygen octahedra. Because of the involvement of both the distortion and the displacement, their competition should be expected in the formation of the COO state. However, the detailed features of the competition have not been understood yet. Thus, the crystallographic features of the COO state in SSMO have been examined by x-ray powder diffraction and transmission electron microscopy. It was found that, when the Sm content increased from x = 0 at room temperature, the DC state changed into the COO state with the tetragonal symmetry around x = 0.13. The notable feature of the COO state is that the state is characterized by a nanometer-scaled banded structure consisting of an alternating array of two tetragonal bands. One tetragonal band consisted of the COO state involving both the Jahn-Teller distortion and the R25-type rotational displacement. But, there was only the latter displacement in the other, the state of which could be identified as a disordered tetragonal (DT) state. Based on this, it is understood that the COO-state formation from the DC state should take place via the appearance of the DT state, which may involve fluctuations of the C-type orbital ordering.

Characteristic Features of the C-Type Orbital-Ordered State in the Simple Perovskite Manganite Sr1-xNdxMnO3

2014 ◽  
Vol 922 ◽  
pp. 626-631
Author(s):  
Hiroki Sato ◽  
Yasuhide Inoue ◽  
Yasumasa Koyama
Keyword(s):  
Crystal Structure ◽  
Tetragonal Symmetry ◽  
Perovskite Manganite ◽  
Teller Distortion ◽  
Rotational Displacement ◽  
Type Orbital ◽  
The Matrix ◽  
Jahn Teller ◽  
Coexistence State ◽  
Jahn Teller Distortion

In the highly-correlated electronic system Sr1-xNdxMnO3, the C-type orbital-ordered (COO) state is present for 0.15<x<0.38, and its crystal structure with the tetragonal-I4/mcmsymmetry involves both theR25-type rotational displacement of MnO6octahedra and the Jahn-Teller distortion as a response of a lattice system to orbital ordering. To understand the details of the competition between the rotational displacement and the Jahn-Teller distortion, the formation of the COO state from the disordered cubic (DC) state with the space groupPm3mhas been investigated mainly by transmission electron microscopy. It was found that, when the temperature was lowered from the DC state forx= 0.20, for instance, COO regions with the tetragonal symmetry, exhibiting a {110}DCbanded structure, were locally formed in the matrix below about 330 K. The subsequent aging at 300 K resulted in the growth of COO regions; that is, the time-relaxation phenomenon. Because of the presence of antiphase boundaries for the rotational displacement in the matrix, the crystal structure of the matrix should also have the tetragonal symmetry. In other words, it is understood that the coexistence state appearing just after cooling from the DC state consists of two tetragonal regions with different c/a values. The coexistence state is apparently characteristic of the competition between the rotational displacement and the Jahn-Teller distortion for the formation of the COO state.

Possible Orbital-Ordered State in the Highly-Correlated Electronic Material Sr1-xCexMnO3

2014 ◽  
Vol 922 ◽  
pp. 230-236
Author(s):  
Takehiro Hanaoka ◽  
Yasuhide Inoue ◽  
Yasumasa Koyama
Keyword(s):  
Room Temperature ◽  
Three Dimensional ◽  
Electronic System ◽  
Careful Analysis ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Diffraction Patterns ◽  
Highly Correlated

The simple perovskite manganite Sr1-xCexMnO3 (SCMO) has a highly-correlated electronic system with a three-dimensional character. Because the presence of orbital-ordered states of eg electrons can be expected in SCMO, the crystallographic features of SCMO samples with 0.09 ≤ x ≤ 0.20 have been investigated mainly by transmission electron microscopy. In addition to fundamental reflections due to the simple perovskite structure, their electron diffraction patterns at room temperature exhibited both the presence of superlattice reflections at k = ()c in the cubic notation and the splitting of fundamental and superlattice reflections. The careful analysis of these reflections indicated that the superlattice reflections originated from the R25-type rotational displacement of oxygen octahedra about one of the <100>c directions. On the other hand, the splitting of the reflections was found to be due to a {110}c banded structure consisting of two tetragonal bands with different c/a values.　Because one of two tetragonal bands had the c/a value of about 1.028, the splitting reflects the introduction of the Jahn-Teller distortion as a response of a lattice system to orbital ordering. It is thus understood that the C-type orbital ordering of eg electrons should be involved in the state at room temperature for 0.09 ≤ x ≤ 0.20 in SCMO.

Crystallographic Features of the C-Type Orbital-Ordered, and Charge- and Orbital-Ordered States in the Simple Perovskite Manganite Ca1-xLaxMnO3

2012 ◽  
Vol 706-709 ◽  
pp. 1612-1617
Author(s):  
Yasuhide Inoue ◽  
Masazumi Arao ◽  
Daisuke Shiga ◽  
Yasumasa Koyama
Keyword(s):  
Three Dimensional ◽  
Electronic System ◽  
Lattice System ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
Transverse Lattice ◽  
Type Orbital ◽  
Antiferromagnetic Ordering ◽  
Monoclinic Distortion ◽  
Highly Correlated

The C-type orbital-ordered (CTOO), and charge-and orbital-ordered (COO) states are present in the simple perovskite manganite Ca1-xLaxMnO3, which has a three-dimensional highly-correlated electronic system. In this study, the crystallographic features of the CTOO and COO states have been investigated mainly by transmission electron microscopy to understand responses of a lattice system to these orderings. Of these two states, the cooling from the disordered orthorhombic Pnma (DO) state around x = 0.20 resulted in the CTOO state with the monoclinic P21/m symmetry. As a result of the monoclinic distortion as a response of the lattice system, the CTOO state consisted of a banded structure that was characterized by an alternating array of two monoclinic domains with different β values. In 0.30 < x < 0.50, on the other hand, the appearance of the COO state from the DO state on cooling accompanied a transverse lattice modulation with q = []DO as a response to orbital ordering in the COO state. The subsequent cooling in the COO state led to the antiferromagnetic ordering with a large lattice dilatation. In other words, no change in the crystal symmetry occurs in the appearance of the antiferromagnetic ordering.

scholarly journals Electric-Field Control of Magnetization, Jahn-Teller Distortion, and Orbital Ordering in Ferroelectric Ferromagnets

2019 ◽  
Vol 122 (24) ◽  
Author(s):  
Lan Chen ◽  
Changsong Xu ◽  
Hao Tian ◽  
Hongjun Xiang ◽  
Jorge Íñiguez ◽  
...  
Keyword(s):  
Electric Field ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Field Control ◽  
Jahn Teller ◽  
Jahn Teller Distortion

THE ORBITAL ORDERING OF THE CUBIC KCrF3

2012 ◽  
Vol 26 (04) ◽  
pp. 1150025 ◽  
Author(s):  
MINPING ZHANG ◽  
GUANGTAO WANG
Keyword(s):  
Electron Correlation ◽  
First Principles ◽  
Theoretical Calculations ◽  
Cubic Phase ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion ◽  
First Principles Method

The electronic, magnetic and orbital structures of KCrF 3 in the cubic phase are studied by first principles method. In the cubic phase, the three Cr - F bonds distance are equal. If the Jahn–Teller distortion is the origin of the orbital polarization, the orbital ordering would disappear. However, our theoretical calculations show that the orbital ordering exists even without the Jahn–Teller distortion. By studying how the orbital polarization changes with the electron correlation and the Jahn–Teller distortion, we found that the origin of the orbital polarization should be the electron correlation and the Jahn–Teller distortion can reinforced such polarization.

Crystallographic features of orbital ordering related to the C-type antiferromagnetic state in the simple perovskite manganite Ca1-xPrxMnO3

MRS Advances ◽  
2016 ◽  
Vol 1 (9) ◽  
pp. 579-584 ◽  
Author(s):  
Kentaro Kojima ◽  
Yasuhide Inoue ◽  
Yasumasa Koyama
Keyword(s):  
State Formation ◽  
Powder Diffraction ◽  
Electronic System ◽  
Perovskite Manganites ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
X Ray ◽  
Notable Feature ◽  
Type Orbital ◽  
Antiferromagnetic Ordering

ABSTRACTIn the highly-correlated electronic system Ca1-xPrxMnO3 having the simple perovskite structure, it has been reported that there exists the C-type orbital-ordered (COO) state accompanying an antiferromagnetic ordering for 0.10 ≤ x ≤ 0.25. According to the previous studies concerning orbital-ordered states in simple perovskite manganites, the COO state was understood to be characterized by a spatial array of (3z2-r2)-type orbitals for 3d electrons in Mn ions. The notable feature of the COO state in Ca1-xPrxMnO3 is that the state with the monoclinic-P21/m symmetry appears as a result of the structural transition from the disordered state with the orthorhombic-Pnma symmetry. Compared with the COO-state formation from the cubic-Pm$\overline 3$m state, however, the formation from the disordered-Pnma state has not been understood yet. We have thus examined the crystallographic features of the formation of the COO state in Ca1-xPrxMnO3, mainly by x-ray powder diffraction and transmission electron microscopy. In the case of x = 0.16, for instance, the COO state was found to appear from the disordered-Pnma state around 90 K on cooling. The notable feature of the formation is that, in the Pnma state just before the COO-state formation, characteristic diffuse scattering appeared around each reflection in electron diffraction patterns, together with the splitting of the 200c reflection in x-ray powder diffraction profiles in the pseudo-cubic notation. Based on these experimental data, it is understood that the formation of the COO state in Ca1-xPrxMnO3 accompanies remarkable fluctuations of the C-type orbital ordering in the disordered-Pnma state.

scholarly journals MEAN-FIELD APPROACH TO CHARGE, ORBITAL, AND SPIN ORDERING IN MANGANITES

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2719-2726 ◽  
Author(s):  
SUDHAKAR YARLAGADDA ◽  
C. S. TING
Keyword(s):  
Nearest Neighbor ◽  
Mean Field Theory ◽  
Mean Field ◽  
Antiferromagnetic Coupling ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Spin Ordering ◽  
Jahn Teller ◽  
Jahn Teller Distortion ◽  
Doping Case

We present a mean-field theory of charge, orbital, and spin ordering in manganites at 50% and 0% dopings by considering Jahn–Teller interaction, nearest-neighbor repulsion, and no single-site double occupancy. For spinless fermions, we show that Jahn–Teller distortion and charge-orbital ordering occur simultaneously. In our two-dimensional model at 50% doping, for small nearest-neighbor repulsion the system is orbitally polarized while for larger repulsion the system undergoes CE type ordering. As for the 0% doping case, the ground state is orbitally antiferromagnetic. Upon including spin degree of freedom, at both 50% and 0% dopings the ordering remains the same at small antiferromagnetic coupling between adjacent core spins.

scholarly journals Absence of Jahn−Teller transition in the hexagonal Ba3CuSb2O9 single crystal

2015 ◽  
Vol 112 (30) ◽  
pp. 9305-9309 ◽  
Author(s):  
Naoyuki Katayama ◽  
Kenta Kimura ◽  
Yibo Han ◽  
Joji Nasu ◽  
Natalia Drichko ◽  
...  
Keyword(s):  
Single Crystal ◽  
Liquid State ◽  
Electron Systems ◽  
Quantum Liquid ◽  
Orbital Ordering ◽  
Spin Orbital ◽  
Teller Distortion ◽  
Single Crystal Study ◽  
Jahn Teller ◽  
Jahn Teller Distortion

With decreasing temperature, liquids generally freeze into a solid state, losing entropy in the process. However, exceptions to this trend exist, such as quantum liquids, which may remain unfrozen down to absolute zero owing to strong quantum entanglement effects that stabilize a disordered state with zero entropy. Examples of such liquids include Bose−Einstein condensation of cold atoms, superconductivity, quantum Hall state of electron systems, and quantum spin liquid state in the frustrated magnets. Moreover, recent studies have clarified the possibility of another exotic quantum liquid state based on the spin–orbital entanglement in FeSc2S4. To confirm this exotic ground state, experiments based on single-crystalline samples are essential. However, no such single-crystal study has been reported to date. Here, we report, to our knowledge, the first single-crystal study on the spin–orbital liquid candidate, 6H-Ba3CuSb2O9, and we have confirmed the absence of an orbital frozen state. In strongly correlated electron systems, orbital ordering usually appears at high temperatures in a process accompanied by a lattice deformation, called a static Jahn−Teller distortion. By combining synchrotron X-ray diffraction, electron spin resonance, Raman spectroscopy, and ultrasound measurements, we find that the static Jahn−Teller distortion is absent in the present material, which indicates that orbital ordering is suppressed down to the lowest temperatures measured. We discuss how such an unusual feature is realized with the help of spin degree of freedom, leading to a spin–orbital entangled quantum liquid state.

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