scholarly journals Nanoscale Phase Separation of Incommensurate and Quasi-Commensurate Spin Stripes in Low Temperature Spin Glass of La2−xSrxNiO4

2021 ◽  
Vol 6 (4) ◽  
pp. 45
Author(s):  
Gaetano Campi ◽  
Antonio Bianconi ◽  
Alessandro Ricci
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Spatial Organization ◽  
Density Wave ◽  
Spin Density Wave ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Strongly Correlated ◽  
Nanoscale Phase Separation ◽  
Striped Phases

While spin striped phases in La2−xSrxNiO4+y for 0.25 < x < 0.33 are the archetypal case of a 1D spin density wave (SDW) phase in doped antiferromagnetic strongly correlated perovskites, few information is available on the SDW spatial organization. In this context, we have measured the spatial variation of the wave vector of the SDW reflection profile by scanning micro X-ray diffractions with a coherent beam. We obtained evidence of a SDW order–disorder transition by lowering a high temperature phase (T > 50 K) to a low temperature phase (T < 50 K). We have identified quasi-commensurate spin stripe puddles in the ordered phase at 50 < T < 70 K, while the low temperature spin glassy phase presents a nanoscale phase separation of T = 30 K, with the coexistence of quasi-commensurate and incommensurate spin stripe puddles assigned to the interplay of quantum frustration and strong electronic correlations.

scholarly journals Direct Visualization of Spatial Inhomogeneity of Spin Stripes Order in La1.72Sr0.28NiO4

2019 ◽  
Vol 4 (3) ◽  
pp. 77 ◽  
Author(s):  
Gaetano Campi ◽  
Nicola Poccia ◽  
Boby Joseph ◽  
Antonio Bianconi ◽  
Shrawan Mishra ◽  
...  
Keyword(s):  
Phase Separation ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Spatial Inhomogeneity ◽  
Strongly Correlated ◽  
Strongly Correlated Electron ◽  
Scale Free ◽  
Spin Order ◽  
Correlated Electron

In several strongly correlated electron systems, the short range ordering of defects, charge and local lattice distortions are found to show complex inhomogeneous spatial distributions. There is growing evidence that such inhomogeneity plays a fundamental role in unique functionality of quantum complex materials. La1.72Sr0.28NiO4 is a prototypical strongly correlated perovskite showing spin stripes order. In this work we present the spatial distribution of the spin order inhomogeneity by applying micro X-ray diffraction to La1.72Sr0.28NiO4, mapping the spin-density-wave order below the 120 K onset temperature. We find that the spin-density-wave order shows the formation of nanoscale puddles with large spatial fluctuations. The nano-puddle density changes on the microscopic scale forming a multiscale phase separation extending from nanoscale to micron scale with scale-free distribution. Indeed spin-density-wave striped puddles are disconnected by spatial regions with negligible spin-density-wave order. The present work highlights the complex spatial nanoscale phase separation of spin stripes in nickelate perovskites and opens new perspectives of local spin order control by strain.

Phase Separation in a Spin Density Wave State of Twisted Bilayer Graphene

JETP Letters ◽  
2020 ◽  
Vol 112 (10) ◽  
pp. 651-656
Author(s):  
A. O. Sboychakov ◽  
A. V. Rozhkov ◽  
K. I. Kugel ◽  
A. L. Rakhmanov
Keyword(s):  
Phase Separation ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Bilayer Graphene ◽  
Wave State ◽  
Twisted Bilayer Graphene

scholarly journals Synthesis of by the Flux Method

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Yuki Maruyama ◽  
Chihiro Izawa ◽  
Tomoaki Watanabe
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
Diffuse Reflectance ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Flux Method ◽  
Phase Crystal ◽  
Euhedral Crystal ◽  
Low Temperature Phase

has been successfully synthesized using Bi2O3–B2O3 eutectic flux. In particular, we succeeded in synthesizing a low-temperature-phase crystal (α-) at 1073 K as well as high-temperature-phase crystal (β-). The morphology of α- and β- particles prepared by the flux method is a euhedral crystal. In contrast, the morphology of particles prepared by solid state reaction differs: α- is aggregated and β- is necked. Ultraviolet-visible diffuse reflectance spectra indicate that the absorption edge is at a longer wavelength for β- than for α- with β- absorbing light of wavelengths up to nearly 400 nm.

scholarly journals Linear magnetoresistance in the low-field limit in density-wave materials

2019 ◽  
Vol 116 (23) ◽  
pp. 11201-11206 ◽  
Author(s):  
Yejun Feng ◽  
Yishu Wang ◽  
D. M. Silevitch ◽  
J.-Q. Yan ◽  
Riki Kobayashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Applied Field ◽  
Density Wave ◽  
Spin Density Wave ◽  
Field Limit ◽  
Fermi Surfaces ◽  
Low Field ◽  
Metallic Charge ◽  
Linear Magnetoresistance

The magnetoresistance (MR) of a material is typically insensitive to reversing the applied field direction and varies quadratically with magnetic field in the low-field limit. Quantum effects, unusual topological band structures, and inhomogeneities that lead to wandering current paths can induce a cross-over from quadratic to linear MR with increasing magnetic field. Here we explore a series of metallic charge- and spin-density-wave systems that exhibit extremely large positive linear MR. By contrast to other linear MR mechanisms, this effect remains robust down to miniscule magnetic fields of tens of Oersted at low temperature. We frame an explanation of this phenomenon in a semiclassical narrative for a broad category of materials with partially gapped Fermi surfaces due to density waves.

Low Temperature Magnetotransport Properties of Polycrystalline Ca3Co4O9

MRS Advances ◽  
2017 ◽  
Vol 2 (23) ◽  
pp. 1237-1242
Author(s):  
David J. Magginetti ◽  
Shrikant Saini ◽  
Ashutosh Tiwari
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Band Structure ◽  
Density Wave ◽  
Spin Density Wave ◽  
Significant Component ◽  
Resistivity Measurements ◽  
Metal To Insulator Transition ◽  
Conventional Behavior ◽  
Physical Features

ABSTRACTCa3Co4O9 (CCO) is a promising material for thermoelectric applications; however, this layered oxide shows a large number of physical features that complicate understanding and systematically improving its properties. A significant component of CCO’s behavior is its magnetotransport properties, particularly in the low temperature region where an incommensurate spin density wave affects its band structure. In order to improve understanding in this area, we perform low temperature magnetoresistance (MR) measurements on a bulk CCO sample. Field-less resistivity measurements confirm the conventional behavior of our sample, with a metal-to-insulator transition at approximately 70 K, and a shoulder indicating ferrimagnetism at 14 K. Resistivity vs. temperature under applied magnetic field show significant MR below around 35 K.

Superprotonic high temperature phase and refinement of the low temperature structure of CsHSeO4

2001 ◽  
Vol 216 (3) ◽  
Author(s):  
M. A. Zakharov ◽  
Sergej I. Troyanov ◽  
Erhard Kemnitz
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Superprotonic Phase

AbstractThe crystal structure of the high temperature superprotonic phase of CsHSeO

Magnetic Phase Diagram and Magnetization Dynamics of Frustrated Spin-Chain Compounds

2009 ◽  
Vol 152-153 ◽  
pp. 233-236 ◽  
Author(s):  
Yu. B. Kudasov
Keyword(s):  
Phase Diagram ◽  
Low Temperature ◽  
Nearest Neighbor ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Magnetization Dynamics ◽  
Ising Spin ◽  
Glauber Theory

The magnetic phase diagram of Ising spin chains packed into the frustrated triangular lattice is discussed. A structure of a low-temperature phase depends strongly on interactions between the next-to-nearest-neighbor chains because they lift the degeneracy of the triangular AFM Ising model. That is why, a variety of low-temperature phases is observed in CsCoCl3, Ca3Co2O6, and Sr5Rh4O12. On the contrary, the high-temperature phase (honeycomb AFM structure) is unique. The frustrated Ising chain systems demonstrate an unusual and very slow magnetization dynamics. A model of the magnetization dynamics similar to the Glauber theory is developed.

Irreversible single-crystal to polycrystal and reversible single-crystal to single-crystal phase transformations in cyanurates

2001 ◽  
Vol 57 (6) ◽  
pp. 791-799 ◽  
Author(s):  
Menahem Kaftory ◽  
Mark Botoshansky ◽  
Moshe Kapon ◽  
Vitaly Shteiman
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Single Crystal ◽  
High Temperature Phase ◽  
Monoclinic Space Group ◽  
Temperature Phase ◽  
Space Group ◽  
Reversible Phase ◽  
Low Temperature Phase

4,6-Dimethoxy-3-methyldihydrotriazine-2-one (1) undergoes a single-crystal to single-crystal reversible phase transformation at 319 K. The low-temperature phase crystallizes in monoclinic space group P21/n with two crystallographically independent molecules in the asymmetric unit. The high-temperature phase is obtained by heating a single crystal of the low-temperature phase. This phase is orthorhombic, space group Pnma, with the molecules occupying a crystallographic mirror plane. The enthalpy of the transformation is 1.34 kJ mol−1. The small energy difference between the two phases and the minimal atomic movement facilitate the single-crystal to single-crystal reversible phase transformation with no destruction of the crystal lattice. On further heating, the high-temperature phase undergoes methyl rearrangement in the solid state. 2,4,6-Trimethoxy-1,3,5-triazine (3), on the other hand, undergoes an irreversible phase transformation from single-crystal to polycrystalline material at 340 K with an enthalpy of 3.9 kJ mol−1; upon further heating it melts and methyl rearrangement takes place.

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