Magnetic structure, magnetoelastic coupling, and thermal properties ofEuCrO3nanopowders

Abstract

We carried out detailed studies of the magnetic structure, magnetoelastic coupling, and thermal properties of EuCrO3 nano-powders from room temperature to liquid helium temperature. Our neutron powder diffraction and X-ray powder diffraction measurements provide precise atomic positions of all atoms in the cell, especially for the light oxygen atoms. The low-temperature neutron powder diffraction data revealed extra Bragg peaks of magnetic origin which can be attributed to a Gx antiferromagnetic structure with an ordered moment of ∼ 2.4 µB consistent with the 3d 3 electronic configuration of the Cr 3+ cations. Apart from previously reported antiferromagnetic and ferromagnetic transitions in EuCrO3 at low temperatures, we also observed an anomaly at about 100 K. This anomaly was observed in temperature dependence of sample's, lattice parameters, thermal expansion, Raman spectroscopy, permittivity and conductance measurements. This anomaly is attributed to the magnetoelastic distortion in the EuCrO3 crystal.

X-ray photoemission spectroscopy investigation of Ce1 −xEuxCrO3nano-powders

“…In the preceding publications, the preparation, characterization, and physical properties of EuCrO 3 and CeCrO 3 were described in detail. Phase purity and morphology of samples were confirmed using X‐ray diffraction, neutron powder diffraction, transmission electron microscopy, and scanning electron microscopy. In order to study the surface of particles, XPS measurements were performed on Kratos ESCA AXIS ULTRA spectrometer, equipped with a hemispherical electron energy analyzer and the monochromatic X‐ray source of Al K α (1486.58 eV) under 5× 10 −9 mbar, at the Max Planck Institute for Solid State Research, Germany.…”

“…In the preceding papers, we confirmed the pure distorted orthorhombic structure of EuCrO 3 and CeCrO 3 nano‐powders (with P b n m space group) while our magnetic studies revealed the existence of the canted antiferromagnetic core surrounded by a thin layer of the spin disorder structure, which has inspired us to analyze the surface of particles.…”

“…The orthorhombic CeCrO 3 and EuCrO 3 compounds have attracted particular attention due to their complex magnetic properties including magnetization reversal, exchange bias effect, sign reversal of exchange bias and magneto‐electric coupling. Out of the perovskite rare earth chromite family, only a few finding have been reported on the study of their core‐level XPS spectra. At present, only one XPS data on EuCrO 3 is available, revealing a thin layer of un‐reacted Eu 2 O 3 and Cr 2 O 3 as well as some traces of Cr metal at their surfaces.…”

Microscopic Approach to the Magnetoelectric Coupling in RCrO3 (R = Y, La, Lu and Eu) Compounds

“…The displacement of the Raman frequencies between Т N and Т * assumes a competition between weak ferromagnetism and antiferromagnetic interaction. Such anomalous behaviour of phonon modes is also observed in EuCrO 3 [18]. In the Raman spectra of RCrO 3 , when R is non-magnetic (Y , La, Lu and Eu), two typical behaviours are observed: 1) below Т N the energy of the phonon mode first increases as around Т * there is a "kink" with additional hardening of the mode and subsequent saturation at very low temperatures; 2) below Т N the energy of the phonon mode first decreases, as around Т * there is a "kink" with an additional frequency increase and subsequent saturation at very low temperatures.…”

High-resolution time of flight neutron diffraction and magnetization studies of spin reorientation and polar transitions in SmCrO3

“…In the situation of K s having opposite signs, easy-cone type anisotropy [59] is expected for K 2 = − 1 2 K 1 to K 2 = ∞ (with K 1 negative), which is practically realized as canted spins [60]. It has been theoretically shown [61] and investigated through microwave spectroscopy studies [62,63] that the SRPT arises due to fourth-order magnetic anisotropy, which is generally small but dominates the orientational behavior when the second-order magnetic anisotropy changes sign [8,64,65].…”