Screened Moments and Extrinsic In-Gap States in Samarium Hexaboride

Published

April 18, 2018

Author(s)

W. T. Fuhrman, J. R. Chamorro, P. A. Alekseev, J.-M. Mignot, T. Keller, Jose Rodriguez Rivera, Yiming Qiu, P. Nikolic, T. M. McQueen, Collin L. Broholm

Abstract

The Kondo impurity effect in metals is the result of quantum-mechanical scattering of conduction electrons by magnetic impurities.¹ This process leads to exotic effects such as unconventional superconductivity and an effective electron mass enhanced by 2-3 orders of magnitude. ^2-3 The small bandgap insulator SmB₆ has long been known to have thermodynamic properties at odds with being an insulator, yet the extensive search for low-enery phenomena which could explain this has remained elusive and controversial even after 50 years of research into its unconventional nature. ^4-9 We have observed a Kondo impurity-like momnet screening effect in the insulating state of nominally pure and Gd-doped SmB₆ via heat capacity, magnetization, and resistivity measurements. High-resolution neutron scattering on the low energy regime confirms directly that no coherent magnetism is evident below the long-lived 13 meV spin exciton, restricting proposals of intrinsic neutral low-energy magnetic excitations. ^10-12 We infer that the mixed valence, strongly-correlated nature of SmB₆ exhibits extreme sensitivity to impurities and defects which induce metal-like bulk properties. The requisite interactions leading to this effect are not unique to SmB₆, suggesting this phenomena may provide an understanding of metallic properties in other correlated insulators. ¹³

Citation

Nature Communications

Volume

9

Issue

1

Pub Type

Journals

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Keywords

Neutron Scattering, magnetic materials, superconductivity.

Citation

Fuhrman, W. , Chamorro, J. , Alekseev, P. , Mignot, J. , Keller, T. , Rodriguez Rivera, J. , Qiu, Y. , Nikolic, P. , McQueen, T. and Broholm, C. (2018), Screened Moments and Extrinsic In-Gap States in Samarium Hexaboride, Nature Communications, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924851 (Accessed April 18, 2024)