On the multiferroic skyrmion-host GaV4S8

Abstract

The lacunar spinel GaV4S8 exhibits orbital ordering at 44 K and shows a complex magnetic phase diagram below 12.7 K, which includes ferromagnetic and cycloidal spin order. At low but finite external magnetic fields, Néel-type skyrmions are formed in this material. Skyrmions are whirl-like spin vortices that have received great theoretical interest because of their non-trivial spin topology and that are also considered as basic entities for new data-storage technologies. Interestingly, we found that the orbitally ordered phase shows sizable ferroelectric polarization and that excess spin-driven polarizations appear in all magnetic phases, including the skyrmion-lattice phase. Hence, GaV4S8 shows simultaneous magnetic and polar order and belongs to the class of multiferroics, materials that attracted enormous attention in recent years. Here, we summarize the existing experimental information on the magnetic, electronic, and dielectric properties of GaV4S8. By performing detailed magnetic susceptibility, resistivity, specific heat, and dielectric experiments, we complement the low-temperature phase diagram. Specifically, we show that the low-temperature and low-field ground state of GaV4S8 seems to have a more complex spin configuration than purely collinear ferromagnetic spin order. In addition, at the structural Jahn-Teller transition the magnetic exchange interaction changes from antiferromagnetic to ferromagnetic. We also provide experimental evidence that the vanadium V4 clusters in GaV4S8 can be regarded as molecular units with spin 1/2. However, at high temperatures deviations in the susceptibility show up, indicating that either the magnetic moments of the vanadium atoms fluctuate independently or excited states of the V4 molecule become relevant.

arXiv comment17 pages, 10 figures, submitted to Phil. Mag

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Cited by in corpus (26)

• Experimental signatures of quantum and topological states in frustrated magnetism
• Polar and magnetic order in GaV4Se8
• Cycloidally modulated magnetic order stabilized by thermal fluctuations in the Néel-type skyrmion host GaV${}_4$S${}_8$
• Assessing exchange-correlation functional performance in the chalcogenide lacunar spinels GaM${}_4$Q${}_8$ (M = Mo, V, Nb, Ta; Q = S, Se)
• Magnetic phases of skyrmion-hosting GaV${}_4$S${}_{8-y}$Se${}_y$ ($y=0,2,4,8$) probed with muon spectroscopy
• Cooperative cluster-Jahn-Teller effect as a possible route to antiferroelectricity
• Possible emergence of a skyrmion phase in ferroelectric GaMo${}_4$S${}_8$
• Magnetic avalanche of non-oxide conductive domain walls
• Orbital-Order Driven Ferroelectricity and Dipolar Relaxation Dynamics in Multiferroic GaMo${}_4$S${}_8$
• Molecular Mott state in the deficient spinel GaV${}_4$S${}_8$
• Lattice dynamics and electronic excitations in a large family of lacunar spinels with a breathing pyrochlore lattice structure
• Structural, magnetic, electric, dielectric, and thermodynamic properties of multiferroic GeV4S8
• Optical conductivity in multiferroic GaV${}_4$S${}_8$ and GeV${}_4$S${}_8$: Phonons and electronic transitions
• Relaxation dynamics of modulated magnetic phases in skyrmion host GaV4S8: an ac magnetic susceptibility study
• Magnetic phase transitions and spin density distribution in the molecular multiferroic GaV${}_4$S${}_8$ system
• Weak ferromagnetism and glassy state in kappa-(BEDT-TTF)2Hg(SCN)2Br
• Structural, magnetic and insulator-to-metal transitions under pressure in the GaV4S8 Mott insulator: A rich phase diagram up to 14.7 GPa
• Magnetoentropic mapping and computational modeling of cycloids and skyrmions in the lacunar spinels GaV${}_4$S${}_8$ and GaV${}_4$Se${}_8$
• Establishing magneto-structural relationships in the solid solutions of the skyrmion hosting family of materials: GaV${}_4$S${}_{8-y}$Se${}_y$
• Excitations and relaxation dynamics in multiferroic GeV4S8 studied by THz and dielectric spectroscopy
• Charge density functional plus $U$ calculation of lacunar spinel GaM${}_4$Se${}_8$ (M = Nb, Mo, Ta, and W)
• Robust cycloid crossover driven by anisotropy in the skyrmion host GaV${}_4$S${}_8$
• Investigation of the magnetic ground state of GaV${}_4$S${}_8$ using powder neutron diffraction
• Resonating holes vs molecular spin-orbit coupled states in group-5 lacunar spinels
• Spin dynamics in the skyrmion-host lacunar spinel GaV4S8
• Optical, dielectric, and magnetoelectric properties of ferroelectric and antiferroelectric lacunar spinels