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Structure and magnetism of collapsed lanthanide elements

DOI: 10.1103/PhysRevB.100.024107 DOI Help

Authors: M. I. Mcmahon (University of Edinburgh) , S. Finnegan (University of Edinburgh) , R. J. Husband (University of Edinburgh) , K. A. Munro (University of Edinburgh) , E. Plekhanov (King's College London) , N. Bonini (King's College London) , C. Weber (King's College London) , M. Hanfland (European Synchrotron Radiation Facility) , U. Schwarz (Max Planck Institut für Chemische Physik fester Stoffe) , S. G. Macleod (Atomic Weapons Establishment)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Physical Review B , VOL 100

State: Published (Approved)
Published: July 2019

Abstract: Using synchrotron x-ray diffraction, we show that the long-accepted monoclinic structure of the “collapsed” high-pressure phases reported in seven lanthanide elements [Nd, Tb, Gd, Dy, Ho, Er, and (probably) Tm] is incorrect. In Tb, Gd, Dy, Ho, Er, and Tm we show that the collapsed phases have a 16-atom orthorhombic structure ( o F 16 ) not previously seen in the elements, whereas in Nd we show that it has an eight-atom orthorhombic structure ( o F 8 ) previously reported in several actinide elements. o F 16 and o F 8 are members of a new family of layered elemental structures, the discovery of which reveals that the high-pressure structural systematics of the lanthanides, actinides, and group-III elements (Sc and Y) are much more related than previously imagined. Electronic structure calculations of Tb, combined with quantum many-body corrections, confirm the experimental observation, and calculate that the collapsed orthorhombic phase is a ferromagnet, nearly degenerate with an antiferromagnetic state between 60 and 80 GPa. We find that the magnetic properties of Tb survive to the highest pressures obtained in our experiments (110 GPa). Further calculations of the collapsed phases of Gd and Dy, again using the correct crystal structure, show the former to be a type-A antiferromagnet, whereas the latter is ferromagnetic.

Journal Keywords: Electronic structure; Pressure effects; First-principles calculations; Pressure techniques; X-ray diffraction

Diamond Keywords: Ferromagnetism; Antiferromagnetism

Subject Areas: Materials, Physics

Instruments: I15-Extreme Conditions

Other Facilities: ID09 at ESRF

Added On: 01/08/2019 11:28

Discipline Tags:

Quantum Materials Physics Hard condensed matter - structures Magnetism Materials Science

Technical Tags: