Collapse of Magnetic Order in Jarosite

The availability of synchrotron x-ray diffraction, x-ray spectroscopy and infrared spectroscopy  has enabled numerous advances in the physics of materials at extreme conditions, and the physics of materials with correlated electrons and their behavior at high pressure has been an ongoing area of emphasis.  Recently, the Jacobsen group at Northwestern used multiple synchrotron techniques in a study of the frustrated antiferromagnetic material jarosite, KFe3(OH)6(SO4)2.  The work combined results from x-ray diffraction and x-ray emission spectroscopy at the HPCAT sector at the Advanced Photon Source (APS), Argonne National Laboratory, synchrotron Mössbauer spectroscopy at APS Sector 3, and synchrotron IR spectroscopy at the Frontier Infrared Spectroscopy facility at NSLS-II, Brookhaven National Laboratory.  At approximately 45 GPa, the Kagomé net of Fe3+ centers undergoes a collapse of magnetic order, accommodated by the formation of an unusual twisted net in which the triangular geometry of the equilateral triangles of Fe3+ ions is preserved (Fig. 1).

Klein, R. A. et al., Collapse of magnetic order in jarosite. Physical Review Letters 125, 077202 (2020).

Kagome net of Fe(III) centers in jarosite. Top: Structural unit of the net at (left) ambient pressure and (right) 80 GPa. Bottom: Layers of extended nets at (left) ambient pressure and (right) 80 GPa.