Ba3MxTi3−xO9(M=Ir

Abstract

We report the structural and magnetic properties of the 4d (M = Rh) based and 5d (M = Ir) based systems Ba 3 M x Ti 3−x O 9 (nominally x = 0.5, 1). The studied compositions were found to crystallize in a hexagonal structure with the centrosymmetric space group P 6 3 /mmc. The structures comprise of A 2 O 9 polyhedra [with the A site (possibly) statistically occupied by M and Ti] in which pairs of transition metal ions are stacked along the crystallographic c axis. These pairs form triangular bilayers in the ab plane. The magnetic Rh and Ir ions occupy these bilayers, diluted by Ti ions even for x = 1. These bilayers are separated by a triangular layer which is dominantly occupied by Ti ions. From magnetization measurements we infer strong antiferromagnetic couplings for all of the materials but the absence of any spin-freezing or spin-ordering down to 2 K. Further, specific heat measurements down to 0.35 K show no sign of a phase transition for any of the compounds. Based on these thermodynamic measurements we propose the emergence of a quantum spin liquid ground state for Ba 3 Rh 0.5 Ti 2.5 O 9 , and Ba 3 Ir 0.5 Ti 2.5 O 9 , in addition to the already reported Ba 3 IrTi 2 O 9 .

Unconventional magnetism in the 4d4 -based S=1 honeycomb system Ag3Kumar1, Dey2, Ramesha3 et al. 2019Phys. Rev. BSelf Cite190140View full textAdd to dashboardCite

“…The data could be fit to a gapped behaviour with a gap of about 3 K but our heat capacity data show a power-law decrease. Such power law behavior is also seen in other spin liquid candidate materials [12,39].…”

“…Over the past few years, there has been a shift in focus from 3d -based systems to the exploration of 4d and 5d -based ones due to the possibility of strong spin-orbit coupling (SOC) driving exotic magnetism [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The SOC is found to be very strong for 5d-based systems and could stabilize a Mott insulating state as also other novel phases [1,2,6,[12][13][14][15].…”

“…Over the past few years, there has been a shift in focus from 3d -based systems to the exploration of 4d and 5d -based ones due to the possibility of strong spin-orbit coupling (SOC) driving exotic magnetism [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The SOC is found to be very strong for 5d-based systems and could stabilize a Mott insulating state as also other novel phases [1,2,6,[12][13][14][15]. Issues such as the realization of the J ef f = 1/2 state for the d 5 configuration (half-filled) [2], possible realization of the Kitaev model [16] in d 5 Mott insulators [5,17], and the emergence of spin-liquid states in triangular lattice materials have been widely explored for Ir-based materials [6,7,12,18,19].…”

“…The SOC is found to be very strong for 5d-based systems and could stabilize a Mott insulating state as also other novel phases [1,2,6,[12][13][14][15]. Issues such as the realization of the J ef f = 1/2 state for the d 5 configuration (half-filled) [2], possible realization of the Kitaev model [16] in d 5 Mott insulators [5,17], and the emergence of spin-liquid states in triangular lattice materials have been widely explored for Ir-based materials [6,7,12,18,19].…”

Dynamic magnetism in the disordered hexagonal double perovskite BaTi1/2Mn1/2O3

“…The existence of residual entropy is compatible with a spin glass and the dynamic magnetism probed by the ZF spectra at 0.019 K could be due to the fraction of spins that are not frozen due a distribution of time scales in a spin glass. However, residual entropy is also observed in spin liquid candidates [47,48]. In short, the low-T dynamic magnetic state in our system displays spin liquid behavior, although a spin glass state, induced by the disordered lattice of orphans and trimers [41][42][43], is a strong candidate to interpret our results.…”