Magnetic properties of an amorphous antiferromagnet

Walstedt, R. E. ; Kummer, R. B. ; Geschwind, S. ; Narayanamurti, V. ; Devlin, G. E. (1979) Magnetic properties of an amorphous antiferromagnet Journal of Applied Physics, 50 (B3). pp. 1700-1705. ISSN 0021-8979

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We present measurements and a theoretical analysis of the magnetic properties of dilute neutral (In) donors in CdS, which we demonstrate to be a well-characterized example of an amorphous antiferromagnet with spins S=1/2. High-quality data for relative values of sample magnetization have been obtained by the Faraday rotation method at temperatures ranging from 55 mK to 2.5 K and fields up to 15 kG. Data are given for crystals with neutral donor concentrations of 8.1016/cm3 and 2.1.1017/cm3. The susceptibility, ?, increases monotonically with decreasing T with no evidence of ordering, even though the median exchange coupling is -7 K. A model Hamiltonian is derived by scaling calculations of direct exchange for the H2 molecule to the Bohr radius and effective Rydberg of the donor wave functions. A sample of such a Hamiltonian is generated in a computer simulation and solved approximately by dividing the system into clusters (and isolated spins) according to a coupling threshold and solving the cluster Hamiltonians exactly. Inter-cluster interactions are included in a molecular field approximation. Excellent agreement with experiment is found, and X is shown to be dominated by clusters, both even and odd, at all temperatures.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
Keywords:Cadmium Sulfied; Indium; Antiferromagnetism; Amorphous State; Impurities; Magneto-optical Effects; Heisenberg Model
ID Code:87496
Deposited On:19 Mar 2012 06:52
Last Modified:19 Mar 2012 06:52

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