Magnetic phase diagram of the helimagnetic spinel compound ZnCr<sub>2</sub>Se<sub>4</sub>revisited by small-angle neutron scattering

Cameron, A. S.; Tymoshenko, Y. V.; Portnichenko, P. Y.; Gavilano, J. L.; Tsurkan, V.; Felea, V.; Loidl, A.; Жерлицын, С.; Wosnitza, J.; Inosov, D. S.

doi:10.1088/0953-8984/28/14/146001

Cited by 16 publications

(15 citation statements)

References 12 publications

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“…therein). SANS (Cameron et al, 2016) has been used to study the field dependence of the multidomain spin spiral phase with particular focus on a spin nematic phase, proposed at higher field (Felea et al, 2012). A continuous change of magnetic structure is observed as a function of field and temperature while a discontinuous jump of the spiral pitch indicates the domain selection field.…”

Section: Properties Of Non-b20 Spiral Magnets As Inferred From Sansmentioning

confidence: 99%

Magnetic small-angle neutron scattering

et al. 2019

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Small-angle neutron scattering (SANS) is one of the most important techniques for microstructure determination, being utilized in a wide range of scientific disciplines, such as materials science, physics, chemistry, and biology. The reason for its great significance is that conventional SANS is probably the only method capable of probing structural inhomogeneities in the bulk of materials on a mesoscopic real-space length scale, from roughly 1 − 300 nm. Moreover, the exploitation of the spin degree of freedom of the neutron provides SANS with a unique sensitivity to study magnetism and magnetic materials at the nanoscale. As such, magnetic SANS ideally complements more real-space and surface-sensitive magnetic imaging techniques, e.g., Lorentz transmission electron microscopy, electron holography, magnetic force microscopy, Kerr microscopy, or spinpolarized scanning tunneling microscopy. In this review article we summarize the recent applications of the SANS method to study magnetism and magnetic materials. This includes a wide range of materials classes, from nanomagnetic systems such as soft magnetic Fe-based nanocomposites, hard magnetic Nd−Fe−B-based permanent magnets, magnetic steels, ferrofluids, nanoparticles, and magnetic oxides, to more fundamental open issues in contemporary condensed matter physics such as skyrmion crystals, noncollinar magnetic structures in noncentrosymmetric compounds, magnetic/electronic phase separation, and vortex lattices in type-II superconductors. Special attention is paid not only to the vast variety of magnetic materials and problems where SANS has provided direct insight, but also to the enormous progress made regarding the micromagnetic simulation of magnetic neutron scattering.

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Section: Properties Of Non-b20 Spiral Magnets As Inferred From Sansmentioning

confidence: 99%

Magnetic small-angle neutron scattering

et al. 2019

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“…The extent of the bond frustration in ZnCr 2 Se 4 (θ CW /T N ∼ 5.2) is high even compared with other spinel structures. Spin fluctuations in ZnCr 2 Se 4 were observed by diffuse magnetic scattering above T N , suggesting a magnetic microdomain phase below 45 K [21,22]. Further studies conducted between the Curie-Weiss and Néel temperatures revealed the presence of negative thermal expansion below 100 K [16,23], shifting of the magnetic resonance line [20], anomalous behavior of eigenfrequencies of phonon modes [16], and deviation from Curie-Weiss behavior [1], making further investigation with muon spin-relaxation measurements attractive.…”

Section: Introductionmentioning

confidence: 99%

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Zajdel

Beek

et al. 2017

Phys. Rev. B

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The crystal and magnetic structures of stoichiometric ZnCr 2 Se 4 have been investigated using synchrotron x-ray and neutron powder diffraction, muon spin relaxation (µSR), and inelastic neutron scattering. Synchrotron x-ray diffraction shows a spin-lattice distortion from the cubic Fd3m spinel to a tetragonal I 4 1 /amd lattice below T N = 21 K, where powder neutron diffraction confirms the formation of a helical magnetic structure with magnetic moment of 3.04(3) µ B at 1.5 K, close to that expected for high-spin Cr 3+ . µSR measurements show prominent local spin correlations that are established at temperatures considerably higher (<100 K) than the onset of long-range magnetic order. The stretched exponential nature of the relaxation in the local spin-correlation regime suggests a wide distribution of depolarizing fields. Below T N , unusually fast (>100 µs −1 ) muon relaxation rates are suggestive of rapid site hopping of the muons in static field. Inelastic neutron scattering measurements show a gapless mode at an incommensurate propagation vector of k = [000.4648(2)] in the low-temperature magnetic ordered phase that extends to 0.8 meV. The dispersion is modeled by a two-parameter Hamiltonian, containing ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions with a J nnn /J nn =−0.337.

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“…This may have been because the spinel structure had a high cubic symmetry. The SANS measurements also confirmed the isotropic phase transitions with respect to the field direction in the monocrystalline ZnCr 2 Se 4 spinel [ 11 ]. The observed ρ (T) dependence in Figure 5 means that doping of the ZnCr 2 Se 4 single crystals under study with tantalum did not affect the thermal activation of electrical conductivity.…”

Section: Resultsmentioning

confidence: 68%

“…The values of the second critical field, H c 2 , connected with the breakdown of the conical spin structure, drop rapidly with temperature, suggesting a spin frustration of the re-entrant type [ 2 ]. Low-angle neutron scattering (SANS) measurements showed the absence of any long-range magnetic order in the high-field (spin-nematic) phase, as well as the fact that all observed phase transitions were surprisingly isotropic concerning the field direction [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Study of the Structure, Magnetic, Thermal and Electrical Characterisation of ZnCr2Se4: Ta Single Crystals Obtained by Chemical Vapour Transport

et al. 2021

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The new series of single-crystalline chromium selenides, Ta-doped ZnCr2Se4, was synthesised by a chemical vapour transport method to determine the impact of a dopant on the structural and thermodynamic properties of the parent compound. We present comprehensive investigations of structural, electrical transport, magnetic, and specific heat properties. It was expected that a partial replacement of Cr ions by a more significant Ta one would lead to a change in direct magnetic interactions between Cr magnetic moments and result in a change in the magnetic ground state and electric transport properties of the ZnCr2−xTaxSe4 (x = 0.05, 0.06, 0.07, 0.08, 0.1, 0.12) system. We found that all the elements of the cubic system had a cubic spinel structure; however, the doping gain linearly increased the ZnCr2−xTaxSe4 unit cell volume. Doping with tantalum did not significantly change the semiconductor and magnetic properties of ZnCr2Se4. For all studied samples (0 ≤ x ≤ 0.12), an antiferromagnetic order (AFM) below TN~22 K was observed. However, a small amount of Ta significantly reduced the second critical field (Hc2) from 65 kOe for x = 0.0 (ZnCr2Se4 matrix) up to 42.2 kOe for x = 0.12, above which the spin helical system changed to ferromagnetic (FM). The Hc2 reduction can lead to strong competition among AFM and FM interactions and spin frustration, as the specific heat under magnetic fields H < Hc2 shows a strong field decrease in TN.

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Magnetic phase diagram of the helimagnetic spinel compound ZnCr₂Se₄revisited by small-angle neutron scattering

Cited by 16 publications

References 12 publications

Magnetic small-angle neutron scattering

Magnetic small-angle neutron scattering

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Study of the Structure, Magnetic, Thermal and Electrical Characterisation of ZnCr2Se4: Ta Single Crystals Obtained by Chemical Vapour Transport

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Magnetic phase diagram of the helimagnetic spinel compound ZnCr2Se4revisited by small-angle neutron scattering

Cited by 16 publications

References 12 publications

Magnetic small-angle neutron scattering

Magnetic small-angle neutron scattering

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Study of the Structure, Magnetic, Thermal and Electrical Characterisation of ZnCr2Se4: Ta Single Crystals Obtained by Chemical Vapour Transport

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Product

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Magnetic phase diagram of the helimagnetic spinel compound ZnCr₂Se₄revisited by small-angle neutron scattering