Electronic properties of GaV4S8: A percolation approach

Naik, I.; Hansda, S; Rastogi, A. K.

doi:10.1007/s12043-015-1014-8

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…The resistance can be described by ρ ~ exp(T0/T) 1/4 with an exponent parameter T0  610 5 K (solid line in the right inset of Figure 2). There is a number of reports on the resistivity behavior of polycrystalline GaV4S8 [20,21,33,34,35]. In polycrystalline samples, the decrease of the resistivity above the JT transition is not as strong as documented in Figure 2 and the step at the JT transition is well below one decade [35].…”

Section: High-temperature Magnetic Electric and Thermodynamic Propermentioning

confidence: 94%

“…There is a number of reports on the resistivity behavior of polycrystalline GaV4S8 [20,21,33,34,35]. In polycrystalline samples, the decrease of the resistivity above the JT transition is not as strong as documented in Figure 2 and the step at the JT transition is well below one decade [35]. At room temperature, all these studies find energy barriers of the order of 0.14 eV, which decreases significantly on cooling.…”

Section: High-temperature Magnetic Electric and Thermodynamic Propermentioning

confidence: 96%

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On the multiferroic skyrmion-host GaV₄S₈

Widmann

Ruff

Günther

et al. 2016

Philosophical Magazine

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Broadband microwave spectroscopy has been performed on single-crystalline GaV4S8, which exhibits a complex magnetic phase diagram including cycloidal, Néel-type skyrmion lattice, as well as field-polarized ferromagnetic phases below 13 K. At zero and small magnetic fields two collective modes are found at 5 and 15 GHz, which are characteristic of the cycloidal state in this easy-axis magnet. In finite fields, entering the skyrmion lattice phase, the spectrum transforms into a multi-mode pattern with absorption peaks near 4, 8, and 15 GHz. The spin excitation spectra in GaV4S8 and their field dependencies are found to be in close relation to those observed in materials with Bloch-type skyrmions. Distinct differences arise from the strong uniaxial magnetic anisotropy of GaV4S8 not present in so-far known skyrmion hosts. PACS numbers: 76.50.+g, 12.39.Dc, 75.30.Gw The occurence of nontrivial topology in the spin pattern of magnets has gained considerable interest in condensed matter physics. Recent research focuses on magnetic skyrmions which are thermodynamically stabilized in compounds with noncentrosymmetric crystal structures , in a limited region of the magnetic field versus temperature phase diagram [1-3]. Skyrmions are whirl-like objects of spins which can crystallize in skyrmion lattices (SkLs) with typical lattice constants from ten to hundred nanometers and give rise to emergent electrody-namics, like the topological Hall effect [4-6] or magnetic monopoles [7]. Individual skyrmions have been proposed as building blocks for novel nanomagnetic storage devices [8, 9]. The SkL has raised high interest for microwave-technology applications after collective spin excitations predicted in the GHz range [10] were evidenced in the insulating chiral magnet Cu 2 OSeO 3 [11-16]. Later it was found that different metallic, semiconducting, and insulating chiral magnets support the same set of characteristic excitations, i.e., three SkL modes characterized as clockwise (CW), counterclockwise (CCW) and breathing (BR) modes, that all follow a universal behavior [17]. Besides the Bloch-type skyrmions reported in the aforementioned works, a Néel-type SkL has recently been discovered in GaV 4 S 8 [18], where the spins rotate radially towards the vortex core. In this semiconductor characterized by V 4 S 4 clusters with spin S = 1 2 [19], a structural Jahn-Teller transition [20] at 44 K is followed by the onset of magnetic order at the Curie temperature T C = 13 K. At the structural transition the lattice is stretched along one of the four body diagonals, resulting in a strongly anisotropic easy-axis magnet. The magnetic multi-domain structure strongly depends on the orientation and strength of the applied magnetic field and gives rise to complex magnetic phase diagrams [see Figures 1(a), 1(c) and 2(a)] including cycloidal (Cyc), SkL, and ferromagnetic (FM) regions. Specifically, the skyrmions do not follow the external magnetic field but are confined to the magnetic easy axes. The phases have been interpreted in terms of a comp...

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Section: High-temperature Magnetic Electric and Thermodynamic Propermentioning

confidence: 94%

Section: High-temperature Magnetic Electric and Thermodynamic Propermentioning

confidence: 96%

On the multiferroic skyrmion-host GaV₄S₈

Widmann

Ruff

Günther

et al. 2016

Philosophical Magazine

View full text Add to dashboard Cite

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Monte Carlo simulation of charge transport in disordered organic systems using buffer lattice at the boundary

2019

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In this article, we present an alternative method for simulating charge transport in disordered organic materials by using a buffer lattice at the boundary. This method does not require careful tracking of carrier's hopping pattern across boundaries. Suitability of this method is established by reproducing the field dependence of mobility, carrier relaxation and carrier diffusion in disordered organic systems obtained by simulating the charge transport for the full length of the systems along the field direction without any boundary condition. The significance of the buffer lattice is emphasized by simulating field dependence of mobility without using a buffer lattice, which results in negative field dependence of mobility (NFDM) at low field regime due to the extra bias the carrier gains from the neglected hops at boundaries along field direction.

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