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DOE OSTI · 1607469

Possible Quantum Paramagnetism in Compressed Sr 2 IrO 4

Haskel, D.·Fabbris, G.·Kim, J. H.·Veiga, L. S. I.·Mardegan, J. R. L.·Escanhoela, C. A.·Chikara, S.·Struzhkin, V.·Senthil, T.·Kim, B. J.·Cao, G.·Kim, J. -W.
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Abstract

The result of compression on the magnetic ground state of Sr 2 IrO 4 is studied with x-ray resonant techniques in the diamond anvil cell. The weak interlayer exchange coupling between square-planar 2D IrO 2 layers is easily modified upon compression, with a crossover between magnetic structures around 7 GPa mimicking the effect of an applied magnetic field at ambient pressure. Higher pressures drive an order-disorder magnetic phase transition with no magnetic order detected above 17–20 GPa. The persistence of strong exchange interactions between J eff = 1 / 2 magnetic moments within the insulating IrO 2 layers up to at least 35 GPa points to a highly frustrated magnetic state in compressed Sr 2 IrO 4 , opening the door for realization of novel quantum paramagnetic phases driven by extended 5 d orbitals with entangled spin and orbital degrees of freedom.

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36 MATERIALS SCIENCE75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

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Haskel, D., Fabbris, G., Kim, J. H., Veiga, L. S. I., Mardegan, J. R. L., Escanhoela, C. A., Chikara, S., Struzhkin, V., Senthil, T., Kim, B. J., Cao, G., Kim, J. -W.. 2020-02-11. Possible Quantum Paramagnetism in Compressed Sr 2 IrO 4. https://doi.org/10.1103/physrevlett.124.067201

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36 MATERIALS SCIENCE↗