Magnetic and transport studies of pureV2O3under pressure

Abstract

We report a systematic study of the resistivity and magnetic susceptibility of pure V,O3, the original Mott-Hubbard system at half filling, for pressures 0(P~25 kbar and temperatures 0.35 T 300 K.We also study {V099Tipp&)203 under pressure in order to elucidate the role of disorder on a metalinsulator transition in the highly correlated limit. Despite the low level of doping, we find that the two systems are very different. We observe a conventional collapsing of the Mott-Hubbard gap only for stoichiometric Vq03, the Ti disorder stabilizes the long-range antiferromagnetic order and a magnetic Slater gap. Moreover, we discover different P-T phase diagrams for the two systems, with a decoupling of the charge and spin degrees of freedom at the approach to the T =0, pressure-driven metal-insulator transition in pure V&03.

Single-crystal growth, crystallography, magnetic susceptibility, heat capacity, and thermal expansion of the antiferromagneticS=1chain compoundCaV2ONiazi1, Bud’ko2, Schlagel3 et al. 2009Phys. Rev. B333550View full textAdd to dashboardCite

“…23,[31][32][33] The transition temperature decreases rapidly under pressure. 34 A pressure of only 9 kbar lowers the transition temperature by 60 K, and the transition is completely suppressed at a pressure of Ϸ20 kbar. 34 The transition temperature is also rapidly suppressed if the sample contains V vacancies; a crystal of composition V 1.985 O 3 showed a transition temperature of Ϸ50 K. 33 Furthermore, it was found that when V 2 O 3 is epitaxially grown on LiTaO 3 , the transition temperature is enhanced from the bulk value by 20 K. 25 Given the possibilities of compressive or tensile stresses acting on the V 2 O 3 due to the epitaxial relationship of the V 2 O 3 impurity with the CaV 2 O 4 host and the possibility of nonstoichiometry of the V 2 O 3 impurity phase, one can see how the transition temperature of the V 2 O 3 might be depressed or enhanced from the bulk value by Ϸ30 K as we found for the coherently grown V 2 O 3 impurity phases in our two annealed crystals in Sec.…”

Magnetic phase transition inV2O3nanocrystals

“…29,30 This results in zero overall magnetic moment, event though individual layers have a relatively high moment of 1.2 B per vanadium atom. Experiments 31 have shown that the magnetic transition can be shifted to a temperature below 150 K by application of pressure. At a pressure of about 15 kbar the magnetic transition decouples from the metal-insulator transition, and by about 26 kbar, both phase transitions are completely suppressed.…”

Selected studies of magnetism at high pressure

“…This is in contrast to doping narrow band systems where the complications of electronic and structural disorder lead to effects that may not occur with pressure [ 5 ] .…”