Pressure-induced structural distortion ofTbMnO3: A combined x-ray diffraction and x-ray absorption spectroscopy study

Abstract

The variation of electronic states and structural distortion in highly compressed multiferroic TbMnO 3 was probed by x-ray diffraction ͑XRD͒ and x-ray absorption spectroscopy ͑XAS͒ using synchrotron radiation. Refined XRD data enabled observation of a reduced local Jahn-Teller ͑JT͒ distortion of Mn sites within MnO 6 octahedra in TbMnO 3 with increasing hydrostatic pressure. A progressively increasing intensity of the white line in Mn K-edge x-ray absorption spectra of TbMnO 3 was detected with increasing pressure. The absorption threshold of Mn K-edge spectra of TbMnO 3 is shifted toward higher energy, whereas the pre-edge peak is slightly shifted to lower energy with increasing hydrostatic pressure. We provide spectral evidence for pressure-induced bandwidth broadening for mangnites. The enhanced intensity of the white line and the shifted absorption threshold of Mn K-edge spectra are explained in terms of a reduced JT distortion of MnO 6 octahedra in compressed TbMnO 3. Comparison of XAS data with full-multiple-scattering calculations using code FDMNES shows satisfactory agreement between experimental and calculated Mn K-edge spectra.

Dynamic and structural properties of orthorhombic rare-earth manganites under high pressure

“…Ultimately, for DyMnO 3 , the nearly isotropic compression suggests that the Jahn-Teller distortion hardly changes. This is in good qualitative agreement with the (limited) data on Mn-O2 bond lengths measured by Rietveld refinements for LaMnO 3 , TbMnO 3 , DyMnO 3 , and GdMnO 3 [5,12,13,15].…”

“…In contrast, only a couple of works have been reported on other manganites. Combined x-ray diffraction and x-ray absorption spectroscopy studies on TbMnO 3 and DyMnO 3 showed a gradual decrease of the Jahn-Teller distortion and a bandwidth broadening, but could not clarify the presence of insulator-to-metal transition itself [12,13]. High-pressure Raman studies of TbMnO 3 and PrMnO 3 up to 10 GPa [14] were focused on the compression mechanisms as inferred from the pressure evolution of Raman wave numbers.…”

Giant spin-driven ferroelectric polarization in TbMnO3 under high pressure

“…First, we optimized internal atomic parameters imposing the A-AFM spin configuration, whereas we took the experimental lattice parameters under pressure from ref. 24 (note that measurements have been done at room temperature). We also extracted additional sets of lattice parameters by linearly interpolating experimental values.…”

“…In RMnO 3 , it is well known that the lattice contraction by chemical pressure, that is, substitution of R site with smaller rare-earth, mainly causes the decrease of the Mn-OMn bond angles 9 . In contrast, the application of physical pressure shortens Mn-O bond lengths but increases the Mn-O-Mn bond angles 24 , so that both J 1 and J 2 are enhanced, therefore making the E-AFM spin configuration unusually stable in TbMnO 3 under pressure. …”

Structural, electronic and optical properties of famatinite and enargite Cu3SbS4 under pressure: A theoretical investigation

“…Structurally, CIS can be viewed as one of derivatives from binary CdTe through isovalent element substitution, and the tetrahedrally coordinated framework is inherited from the parent material. Accordingly, both compounds are composed of high symmetry ACh 4 tetrahedron units and obey the electron octet rule, where A is the cation element and Ch the chalcogen, while different symmetries might occur depending on the ordering of the cations [10]. To meet the desired TW production level in the future, however, CdTe and CIS photovoltaics technologies might run into sustainable problems mainly due to the relative scarcity of In and Te, as well as the toxicity of Cd.…”