Related papers: Orbital-Order Driven Ferroelectricity and Dipolar …
We present a dielectric spectroscopy study of the polar dynamics linked to the orbitally driven ferroelectric transition in the skyrmion host GaV4S8. By combining THz and MHz-GHz spectroscopy techniques, we succeed in detecting the…
We report on THz time-domain spectroscopy on multiferroic GeV4S8, which undergoes orbital ordering at a Jahn-Teller transition at 30.5 K and exhibits antiferromagnetic order below 14.6 K. The THz experiments are complemented by dielectric…
In the present work, we provide results from specific heat, magnetic susceptibility, dielectric constant, ac conductivity, and electrical polarization measurements performed on the lacunar spinel GaV4Se8. With decreasing temperature, we…
The lacunar spinel GeV4S8 undergoes orbital and ferroelectric ordering at the Jahn-Teller transition around 30 K and exhibits antiferromagnetic order below about 14 K. In addition to this orbitally driven ferroelectricity, lacunar spinels…
Polar lacunar spinels, such as GaV$_4$S$_8$ and GaV$_4$Se$_8$, were proposed to host skyrmion phases under magnetic field. In this work, we put forward, as a candidate for N\'eel-type skyrmion lattice, the isostructural GaMo$_4$S$_8$, here…
We report on optical spectroscopy on the lacunar spinels GaV$_4$S$_8$ and GeV$_4$S$_8$ in the spectral range from 100 to 23000 cm$^{-1}$ and for temperatures from 5 to 300 K. These multiferroic spinel systems reveal Jahn-Teller driven…
The Jahn-Teller effect refers to the symmetry-lowering geometrical distortion in a crystal (or non-linear molecule) due to the presence of a degenerate electronic state. Usually, the Jahn-Teller distortion is not polar. Recently, GaV4S8…
The lacunar spinel GaNb$_4$Se$_8$ is a tetrahedral cluster Mott insulator where spin-orbit coupling on molecular orbitals and Jahn-Teller energy scales are competitive. GaNb$_4$Se$_8$ undergoes a structural and anti-polar ordering…
We report the observation of an antipolar phase in cubic GaNb$_4$S$_8$ driven by an unconventional microscopic mechanism, the cooperative Jahn-Teller effect of Nb$_4$S$_4$ molecular clusters. The assignment of the antipolar nature is based…
Although multiferroics have undergone extensive examination for several decades, the occurrence of ferroelectricity induced by orbital order is only scarcely documented. In this study, we propose the existence of spontaneous ferroelectric…
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, N\'eel-type skyrmions…
We report a novel dielectric anomaly around the Jahn-Teller orbital order-disorder transition temperature T_JT in LaMnO_(3+delta). The transition has been characterized by resistivity (rho)versus temperature (T), calorimetry, and…
Temperature dependences of a magnetic and an orbital Bragg reflection at the Mn L2 and L3 edges of La0.5Sr1.5MnO4 have been collected. The temperature evolution of the orbital reflection depend strongly on the x-ray energy and reflects the…
Motivated by recent experiments, we present a comprehensive theoretical study of the geometrically frustrated strongly correlated magnetic insulator Mn$_3$O$_4$ spinel oxide based on a microscopic Hamiltonian involving lattice, spin and…
We present dielectric, polarization, resistivity, specific heat, and magnetic susceptibility data on single crystals of the lacunar spinels GaNb4Se8 and GaTa4Se8, tetrahedral cluster-based materials with substantial spin-orbit coupling. We…
Skyrmions are whirl like topological spin objects with high potential for future magnetic data storage. It is a fundamental question, relevant for both basic research and application, if a ferroelectric (FE) polarization can be associated…
The spinel FeV2O4 is known to exhibit peculiar physical properties, which is generally ascribed to the unusual presence of two cations showing a pronounced interplay between spin, orbital and lattice degrees of freedom (Fe2+ and V3+ on the…
We show how low-energy electronic models derived from the first-principles electronic structure calculations can help to rationalize the magnetic properties of two lacunar spinel compounds GaM4S8 with light (M=V) and heavy (M=Mo)…
Exotic quantum phases, arising from a complex interplay of charge, spin, lattice and orbital degrees of freedom, are of immense interest to a wide research community. A well-known example of such an entangled behavior is the Jahn-Teller…
Using a combination of resistance fluctuation (noise) and dielectric spectroscopy we investigate the nature of relaxor-type electronic ferroelectricity in the organic conductor $\kappa$-(BETS)$_2$Mn[N(CN)$_2$]$_3$, a system representative…