Magnetic properties of disordered Ni₃C

Authors

Lanping Yue, University of Nebraska-LincolnFollow
R. Sabiryanov, Department of Physics & Astronomy and Center for Materials Research & Analysis, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0111
E.M. Kirkpatrick, Department of Physics, Rose-Hulman Institute of Technology, Terre Haute, IN 47803
Diandra Leslie-Pelecky, University of Nebraska -- LincolnFollow

Date of this Version

10-1-2000

Comments

Published by American Physical Society. Phys. Rev. B 62, 8969-8975 (2000). http://prb.aps.org. Copyright © 2000 American Physical Society. Permission to use.

Abstract

The metastable Ni₃C phase has been produced by mechanically alloying Ni and C. Ni₃C particles of diameter 10 nm are produced after 90 h of mechanical alloying with no evidence of crystalline Ni in x ray or electron diffraction. Linear muffin-tin orbital band-structure calculations show that Ni₃C is not expected to be ferromagnetic due to strong Ni-C hybridization in the ordered alloy; however, the introduction of even small amounts of disorder produces locally Ni-rich regions that can sustain magnetism. Mechanically alloyed Ni₃C is ferromagnetic, with a room-temperature coercivity of 70 Oe and a magnetization of 0.8 emu/g at 5.5 T, although the hysteresis loop is not saturated. The theoretical prediction that interacting locally nickel-rich regions may be responsible for ferromagnetic behavior is supported by the observation of magnetically glassy behavior at low magnetic fields.