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Title: Balancing structural distortions via competing 4f and itinerant interactions: A case of polymorphism in magnetocaloric HoCo 2

The nature of multiple magnetostructural transformations in HoCo 2 has been studied by employing magnetic and specific heat measurements, temperature and magnetic field dependent X-ray powder diffraction, and first-principles calculations. Unexpected increase of magnetization observed below the spin-reorientation temperature (T SR) suggests that the low-temperature transition involves a reduction of Co moment. First principles calculations confirm that the paramagnetic cubic to ferrimagnetic tetragonal transformation at T C is assisted by itinerant electron metamagnetism, and that the reduction of Co moment in HoCo 2 occurs in parallel with the ferrimagnetic tetragonal to the nearly ferromagnetic orthorhombic transformation at T SRvia the rearrangement of both 3d states of Co and 5d states of Ho. The ac magnetic susceptibility measurements show significant magnetic frustration below T C. Furthermore, in contrast to earlier reports neither ac nor dc magnetic susceptibilities show anomalies in the paramagnetic region obeying the Curie–Weiss law.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-8979
Journal ID: ISSN 2050-7526; JMCCCX
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. C
Additional Journal Information:
Journal Volume: 4; Journal Issue: 20; Journal ID: ISSN 2050-7526
Publisher:
Royal Society of Chemistry
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1254310