Easy-cone magnetic structure in (Cr0.9B0.1)Te

He, Yangkun; Fecher, Gerhard H.; Kroder, Johannes; Borrmann, Horst; Wang, Xiao; Zhang, Lunyong; Kuo, Chang‐Yang; Liu, Cheng-En; Chen, Chien‐Te; Chen, Kai; Choueikani, Fadi; Ohresser, P.; Tanaka, A.; Hu, Z.; Felser, Claudia

doi:10.1063/5.0002118

Cited by 8 publications

(8 citation statements)

References 18 publications

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“…The Rietveld refinement shows that the spins from Cr1 (0, 0, 0) and Cr2 (0, 0, 0.5) are ordered along the c axis at 150 K ferromagnetically, and the magnetic moment of Cr is determined to be 1.87(3) μ B . Schematically, the spin structure of CrTe 0.9 Se 0.1 at 150 K is shown in the inset of Figure (b), which is in good accordance with the magnetic ground state reported previously. ,,− …”

Section: Results and Discussionsupporting

confidence: 89%

Large Linear Negative Thermal Expansion in NiAs-type Magnetic Intermetallic Cr–Te–Se Compounds

Zheng

Yang

et al. 2020

Inorg. Chem.

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A large linear negative thermal expansion (NTE) and expanded NTE temperature range (ΔT NTE) were obtained in magnetoelastic CrTe1–x Se x (0 ≤ x ≤ 0.15) compounds. For CrTe compound, its thermal expansion coefficient of volume (αV) was calculated to be −28.8 ppm K–1 with the temperature ranging from 280 to 340 K. Substituting Te with Se atoms, the NTE behavior and magnetic properties can be well manipulated. With increasing Se in CrTe1–x Se x (0 ≤ x ≤ 0.15) compounds, the ΔT NTE increases from 60 K (280–340 K for x = 0), to 80 K (240–320 K for x = 0.05), to 95 K (200–295 K for x = 0.1), and finally to 100 K (170–270 K for x = 0.15). Furthermore, a linear NTE remains independent of temperature for samples with x ≤ 0.1. The relationship between tunable NTE and magnetic properties was analyzed in detail, indicating that the NTE in CrTe1–x Se x compounds originates from the magnetovolume effect (MVE).

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Section: Results and Discussionsupporting

confidence: 89%

Large Linear Negative Thermal Expansion in NiAs-type Magnetic Intermetallic Cr–Te–Se Compounds

Zheng

Yang

et al. 2020

Inorg. Chem.

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“…Larger values of the topological Hall effect are also observed in thin films [36] , which disappear when the thickness increases, indicating that the topological Hall effect is sensitive to the lattice constant, which is easily affected by strain. The small applied field is due to vanishing small single-ion anisotropy of Cr 3+ ions (3d 3 ) with a negligible orbital moment [33] . Note that the B significantly increases the Cr moment from 2.7 μB in the binary compound [28] to 3.1 μB here, and decreases the magnetocrystalline anisotropy K1 from 500 kJ m -3 [31] to -100 kJ m -3 at 2 K.…”

Section: Figmentioning

confidence: 99%

“…A canted ferromagnetic structure at low temperature was observed by neutron diffraction [32] and magnetization measurements, [28] which could lead to a possible real-space Berry phase and a topological Hall effect, providing a candidate material for skyrmion bubbles. In a previous study, we reported the magnetic structure of (Cr0.9B0.1)Te [33] . Owing to the difficulty in synthesizing stoichiometric CrTe, the chromium vacancies are filled by boron, stabilizing the hexagonal structure as well as shifting the Fermi energy to modify the magnetism.…”

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confidence: 99%

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Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Kroder

Gayles

et al. 2020

Applied Physics Letters

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The Berry phase understanding of electronic properties has attracted special interest in condensed matter physics, leading to phenomena such as the anomalous Hall effect and the topological Hall effect. A non-vanishing Berry phase, induced in momentum space by the band structure or in real space by a non-coplanar spin structure, is the origin of both effects. Here, we report a sign conversion of the anomalous Hall effect and a large topological Hall effect in (Cr0.9B0.1)Te single crystals. The spin reorientation from an easy-axis structure at high temperature to an easy-cone structure below 140 K leads to conversion of the Berry curvature, which influences both, anomalous and topological, Hall effects in the presence of an applied magnetic field and current. We compare and summarize the topological Hall effect in four categories with different mechanisms and have a discussion into the possible artificial fake effect of topological Hall effect in polycrystalline samples, which provides a deep understanding of the relation between spin structure and Hall properties.In condensed matter physics, Berry phases have enabled a wider understanding of many physical concepts and phenomena, such as chiral anomalies [1,2] , magnetic monopoles [3] , and the anomalous Nernst effect [4] . Among them, the intrinsic anomalous Hall effect (AHE) requires the absence of time reversal symmetry and the orbital degeneracy to be lifted. The former is usually seen in ferromagnetic systems but also can be found in specific antiferromagnetic systems. The latter is due to relativistic effects such as the spin-orbit interaction, but can also be induced by a non-collinear magnetic spin texture [5,6] . The combination of these phenomena leads to momentumspace Berry curvature as a linear response to an applied electric field [7,8] . However, a real-space Berry phase originating from non-coplanar spin texture or magnetic topological excitations like

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“…Such features can be attributed to a change in magnetocrystalline anisotropy with temperature and we interpret this to be a spin-reorientation temperature T srt , from easy-axis to easy-cone anisotropy, a feature which is not uncommon for permanent magnets (e.g. Fe 5 SiB 2 [35], MnBi [36], Cr 0.9 B 0.1 Te [37], Gd [38] and the celebrated Nd 2 Fe 14 B [39]). Before presenting further results supporting a claim of a temperature induced spinreorientation, we draw attention to the fact that for a hexagonal uniaxial material the magnetic anisotropy energy can be expressed as…”

Section: B Experimental Magnetismmentioning

confidence: 99%

Data-driven design of a new class of rare-earth free permanent magnets

Vishina¹,

Hedlund²,

Shtender³

et al. 2021

Preprint

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A new class of rare-earth-free permanent magnets is proposed. The parent compound of this class is Co3Mn2Ge, and its discovery is the result of first principles theory combined with experimental synthesis and characterisation. The theory is based on a high-throughput/data-mining search among materials listed in the ICSD database. From ab-initio theory of the defect free material it is predicted that the saturation magnetization is 1.71 T, the uniaxial magnetocrystalline anisotropy is 1.44 MJ/m 3 , and the Curie temperature is 700 K. Co3Mn2Ge samples were then synthesized and characterised with respect to structure and magnetism. The crystal structure was found to be the MgZn2-type, with partial disorder of Co and Ge on the crystallographic lattice sites. From magnetization measurements a saturation polarization of 0.86 T at 10 K was detected, together with a uniaxial magnetocrystalline anisotropy constant of 1.18 MJ/m 3 , and the Curie temperature of TC = 359 K. These magnetic properties make Co3Mn2Ge a very promising material as a rare-earth free permanent magnet, and since we can demonstrate that magnetism depends critically on the amount of disorder of the Co and Ge atoms, a further improvement of the magnetism is possible. From the theoretical works, a substitution of Ge by neighboring elements suggest two other promising materials -Co3Mn2Al and Co3Mn2Ga. We demonstrate here that the class of compounds based on T3Mn2X (T = Co or alloys between Fe and Ni; X=Ge, Al or Ga) in the MgZn2 structure type, form a new class of rare-earth free permanent magnets with very promising performance.

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Easy-cone magnetic structure in (Cr0.9B0.1)Te

Cited by 8 publications

References 18 publications

Large Linear Negative Thermal Expansion in NiAs-type Magnetic Intermetallic Cr–Te–Se Compounds

Large Linear Negative Thermal Expansion in NiAs-type Magnetic Intermetallic Cr–Te–Se Compounds

Large topological Hall effect in an easy-cone ferromagnet (Cr0.9B0.1)Te

Data-driven design of a new class of rare-earth free permanent magnets

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