Magnetically driven loss of centrosymmetry in metallic Pb2CoOsO6

Abstract

We report magnetic, transport, neutron diffraction, and muon spin rotation data showing that Pb 2 CoOsO 6 , a metallic double-perovskite with a centrosymmetric space group at room temperature exhibits a continuous second-order phase transition at 45 K to a magnetically ordered state with a noncentrosymmetric space group. The absence of inversion symmetry is very uncommon in metals, particularly metallic oxides. In contrast to the recently reported ferroelectriclike structural transition in LiOsO 3 , the phase transition in Pb 2 CoOsO 6 is driven by a long-range collinear antiferromagnetic order, with propagation vector k = ( 1 2 , 0, 1 2 ), which relieves the frustration associated with the symmetry of the magnetic exchanges. This magnetically driven loss of inversion symmetry represents another frontier in the search for novel metallic behavior.

Quantum materials with strong spin–orbit coupling: challenges and opportunities for materials chemists

“…[54][55][56][57][58] There are many other exotic electronic and magnetic states that have been found in materials with strong spin-orbit coupling which we will not discuss here (see e.g. [59][60][61] ). We also confine ourselves to discussion of bulk materials, though thin films and heterostructures provide unique and exciting access to further tuning parameters and exotic phases.…”

Magnetically induced metal-insulator transition in Pb2CaOsO6

“…We observe anomalies in the lattice constants at the transition, but no change in the crystal symmetry to within the precision of our diffraction measurements. The low degree of frustration makes it unlikely that the structural anomalies are driven by relief of frustration, in contrast to what is pro-posed for Pb 2 CoOsO 6 [13]. On the other hand, the presence of magnetoelastic coupling indicates that the orbitals could play a role in the MIT as has been suggested in frustrated multiorbital 5d 3 double-perovskites [47].…”

“…In Fig. 2 [13] (see Table II for a list of all the refined structural parameters). The monoclinic structure of Pb 2 ZnOsO 6 is typical for many double perovskites [24] and combines octahedral tilting There is no evidence of short-or long-range magnetic order down to 2 K. No anomalies are seen in the lattice parameters between 2 and 300 K (see Fig.…”

“…Recently, we have synthesized under high pressure several new double perovskites containing Os in the 5d 2 electronic configuration [11][12][13][14]. These materials exhibit a variety of unusual and interesting electronic and magnetic phases, such as the magnetically driven loss of centrosymmetry into a polar metal phase that occurs in metallic Pb 2 CoOsO 6 [13].…”

Coupled magnetic and structural phase transitions in the antiferromagnetic polar metal Pb2CoOsO6 under pressure

“…Recently, Princep and coworkers have synthesized a new polar metal Pb 2 CoOsO 6 in which an antiferromagnetic order with magnetic frustration breaks the inversion symmetry 19 . Pb 2 CoOsO 6 crystallizes in a cation-ordered double-perovskite structure.…”