High-Pressure Synthesis, Crystal Structures, and Magnetic Properties of 5d Double-Perovskite Oxides Ca₂MgOsO₆ and Sr₂MgOsO₆

Abstract

Double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 have been synthesized under high-pressure and high-temperature conditions (6 GPa and 1500 °C). Their crystal structures and magnetic properties were studied by a synchrotron X-ray diffraction experiment and by magnetic susceptibility, specific heat, isothermal magnetization, and electrical resistivity measurements. Ca2MgOsO6 and Sr2MgOsO6 crystallized in monoclinic (P21/n) and tetragonal (I4/m) double-perovskite structures, respectively; the degree of order of the Os and Mg arrangement was 96% or higher. Although Ca2MgOsO6 and Sr2MgOsO6 are isoelectric, a magnetic-glass transition was observed for Ca2MgOsO6 at 19 K, while Sr2MgOsO6 showed an antiferromagnetic transition at 110 K. The antiferromagnetic-transition temperature is the highest in the family. A first-principles density functional approach revealed that Ca2MgOsO6 and Sr2MgOsO6 are likely to be antiferromagnetic Mott insulators in which the band gaps open, with Coulomb correlations of ∼1.8-3.0 eV. These compounds offer a better opportunity for the clarification of the basis of 5d magnetic sublattices, with regard to the possible use of perovskite-related oxides in multifunctional devices. The double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 are likely to be Mott insulators with a magnetic-glass (MG) transition at ∼19 K and an antiferromagnetic (AFM) transition at ∼110 K, respectively. This AFM transition temperature is the highest among double-perovskite oxides containing single magnetic sublattices. Thus, these compounds offer valuable opportunities for studying the magnetic nature of 5d perovskite-related oxides, with regard to their possible use in multifunctional devices.

Structural and magnetic properties of the5d2double perovskitesSr2BReO6(Aczel1, Zhao2, Calder3 et al. 2016Phys. Rev. B223244View full textAdd to dashboardCite

“…For example, a low-moment, long-range antiferromagnetic ground state has been reported for Ba 2 CaOsO 6 [27], spin freezing without signs of long-range magnetic order (i.e. spin glass) has been found for Ca 2 MgOsO 6 [28] and Ba 2 YReO 6 [29], and a non-magnetic singlet ground state was proposed for SrLaMgReO 6 [30]. There are also many other 5d…”

The role of nonmagnetic d0 vs. d10 B-type cations on the magnetic exchange interactions in osmium double perovskites

“…As a characteristic structural feature, there are interpenetrating B and B′ face-centered cubic (fcc) sublattices, and their complex magnetic properties are determined by the intricate interplay between the geometrically frustrated intra-sublattice and inter-sublattices exchange interactions, which are correlated with structure distortions [6][7][8][9][10][11]. The well-studied isoelectronic double perovskites Sr 2 FeOsO 6 [12][13][14][15], and Ca 2 FeOsO 6 [3,7] are exemplary.…”

Magnetic order and electronic structure of the5d3double perovskiteSr2ScOsO6

“…Recent experimental investigations have therefore discussed the role of SOC in 4d 3 and 5d 3 double perovskites [9,[16][17][18][19]. Here we investigate the magnetic insulator Sr 2 ScOsO 6 , which has one of the highest known magnetic transition temperatures in double perovskites hosting only one magnetic ion [20,21]. It is the 3d 0 −5d 3 analogue of 3d 3 −5d [22].…”

“…As this article was under review Ref. [21] was published online which reports Sr 2 MgOsO 6 which contains Os 6+ , 5d 2 ions. This material has T N = 110 K, and is the only reported example of a single magnetic ion double perovskite with T N higher than Sr 2 ScOsO 6 .…”