scholarly journals Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet

2021 ◽  
Author(s):  
Oscar Lee ◽  
Jan Sahliger ◽  
Aisha Aqeel ◽  
Safe Khan ◽  
Shinichiro Seki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Saturation Field ◽  
Crystalline Anisotropy ◽  
Resonance Frequencies ◽  
Field Cycling ◽  
Magnetic Insulator

Abstract Recently, it has been shown that the chiral magnetic insulator Cu2OSeO3 hosts skyrmions in two separated pockets in temperature and magnetic field phase space. It has also been shown that the predominant stabilization mechanism for the low-temperature skyrmions (LTS) phase is the crystalline anisotropy in contrast to temperature fluctuations, which stabilize the well established high-temperature skyrmion (HTS) lattice. Here, we report on the gigahertz dynamics in the LTS phase in Cu2OSeO3. The LTS phase is populated via a field cycling protocol with the static magnetic field applied parallel to the h100i crystalline direction of plate and cuboid-shaped bulk crystals. By analyzing temperature-dependent broadband spectroscopy data, clear evidence of low-temperature skyrmion excitations with clockwise (CW), counterclockwise (CCW), and breathing mode (BR) character at temperatures below T = 40 K are shown. We find that the modes’ intensities can be tuned with the number of field-cycles below the saturation field, and by tracking the resonance frequencies, the LTS phase diagram can be established. From our experiments, we conclude that the LTS phase is well separated from the high-temperature phase. Furthermore, by monitoring the strength of the observed hybridization between a dark CW mode and the BR as a function of temperature for the two differently shaped crystals, we unambiguously conclude that the magnetocrystalline anisotropy governs the hybridization.

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.

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

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.

35Cl NQR and Structural Studies of Chloroacetanilides C6H3Cl2NHCOCH3-xClx, 1 ≤ x ≤ 3

1992 ◽  
Vol 47 (1-2) ◽  
pp. 160-170
Author(s):  
Dirk Groke ◽  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Phenyl Group ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Chlorine Atoms ◽  
Space Group ◽  
Low Temperature Phase

AbstractThe temperature dependence of 35Cl NQR frequencies and the phase transition behaviour of chloroacetanilides (N-[2,6-dichlorophenyl]-2-chloroacetamide, -2,2-dichloroacetamide, -2,2,2-trichloroacetamide) were investigated. The crystal structure determination of N-[2,6-dichlorophenyl]- 2-chloroacetamide leads to the following: a = 1893.8 pm, b = 1110.7 pm, c = 472.1 pm, space group P212121 = D24 with Z = 4 molecules per unit cell. The arrangement of the molecules and their geometry is comparable to the high temperature phase of the acetyl compound N-[2,6-dichlorophenyl]- acetamide. For N-[2,6-diclorophenyl]-2,2,2-trichloroacetamide it was found: a = 1016.6 pm, b = 1194.3 pm, c = 1006.7 pm, ß= 101.79°, space group P21/c = C52h, Z = 4. The structure is similar to the low temperature phase of N-[2,6-dichlorophenyl]-acetamide. Parallelism between the temperature dependence of the 35C1 NQR lines of the CCl3 group and the X-ray diffraction results concerning the different behaviour of the chlorine atoms was observed. The structures of the compounds show intermolecular hydrogen bonding of the N - H • • • O - C type. The phenyl group and the HNCO function are nearly planar. A bleaching out of several 35Cl NQR lines at a temperature far below the melting point of the substances was observed. The different types of chlorine atoms (aromatic, chloromethyl) can be distinguished by their temperature coefficients of the 35Cl NQR frequencies. All the resonances found show normal "Bayer" temperature behaviour. N-[2,6-dichlorophenyl]-2,2-diehloroacetamide shows several solid phases. One stable low temperature phase and an instable high temperature phase (at room temperature) were observed. The different phases were detected by means of 35Cl NQR spectroscopy and thermal analysis

V CYCLE DYNAMICAL EXPONENT OF THE MULTI-SCALE-UPDATE ALGORITHM FOR THE 2-d XY MODEL

1993 ◽  
Vol 04 (05) ◽  
pp. 947-954
Author(s):  
S. L. ADLER ◽  
G. V. BHANOT
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Xy Model ◽  
Temperature Phase ◽  
Dynamical Correlation ◽  
Dynamical Exponent ◽  
Multi Scale ◽  
Correlation Exponent ◽  
Low Temperature Phase

We have computed the dynamical correlation exponent for the Multi Scale Algorithm recently proposed by us for the 2-d XY model. We find that z = 1.70 (2) in the high temperature phase and z = 1.60 (2) in the low temperature phase.

Properties of Mg2NiH4 at 450-570 K

1998 ◽  
Vol 513 ◽  
Author(s):  
S. E. Guthrie ◽  
G. J. Thomas ◽  
D. Noreus ◽  
E. Ronnebro
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Thermal Stresses ◽  
Microscopic Analysis ◽  
Hydrogen Desorption ◽  
High Temperature Phase ◽  
Desorption Kinetics ◽  
Temperature Phase ◽  
Monoclinic Distortion ◽  
Kinetics Of

ABSTRACTIt has been established that Mg2NiH4 undergoes a phase change around 500°K in which the orientation of the NiH4 complex is quenched in a monoclinic distortion of the cubic high temperature phase. This results in the formation of domains in which the lattice distortion is accommodated by microtwinning. These effects can be absent when the hydride phase is formed below the transition temperature. Microscopic analysis verifies a similar basal cubic structure in the low temperature phase; however, the domains and microtwins are absent in this material and it can readily be destabilized by thermal stresses induced by the electron beam. It is of interest to measure and compare the effect of the lattice differences on the thermodynamic properties of the low temperature versus the high temperature hydride phases. We report the equilibrium PCT data and hydrogen desorption kinetics of the two hydrides in the temperature range of 450–570 K.

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