Abstract
CoSn is a Pauli paramagnet with relatively flat d bands centered about 100 meV below the Fermi energy, EF. Single crystals of CoSn lightly doped with Fe, In, or Ni are investigated using X-ray and neutron scattering, magnetic susceptibility and magnetization, AC susceptibility, specific heat, and resistivity measurements. Within the rigid-band approximation, hole doping with a few percent of Fe or In should move the flat bands closer to EF, whereas electron doping with Ni should move the flat bands further away from EF. We provide evidence that this indeed occurs. Fe and In doping drive CoSn toward magnetism, while Ni doping suppresses CoSn's already weak magnetic response. The resulting ground state is different for Fe versus In doping. For Fe-doped crystals, Co1-xFexSn, with 0.02<x<0.27, the magnetic and specific-heat data are consistent with the formation of a spin glass, with a glass temperature, Tg, ranging from 1 K for x=0.02 to 10 K for x=0.27. Powder and single-crystal neutron diffraction found no evidence of long-range magnetic order below Tg for samples with x≈0.17. For In-doped crystals, CoSn1-yIny, both the magnetic susceptibility and the Sommerfeld coefficient, γ, increase substantially relative to pure CoSn, but with no clear indication of a magnetic transition for 0.05<y<0.2. CoSn crystals doped with Ni (Co0.93Ni0.07Sn) have a significantly smaller magnetic susceptibility and γ than pure CoSn, consistent with flat bands further from EF.
| Original language | English |
|---|---|
| Article number | 044202 |
| Journal | Physical Review Materials |
| Volume | 5 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 2021 |
Funding
This research was supported almost entirely by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Help with the neutron scattering experiments and data interpretation was provided by Y.H.L., M.B.S., and Q.Z. of the Neutron Scattering Division. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory. This manuscript has been co-authored by employees of UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The U.S. Government retains and the publisher, by accepting the paper for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this paper, or allow others to do so, for U.S. Government purposes.