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Elastic constant measurements of rare earth transition metal compounds
Physica 119B (1983) 130 North-Holland Publishing Company
ELASTIC METAL
CONSTANT
MEASUREMENTS
OF RARE
EARTH
TRANSITION
COMPOUNDS
S.B. PALMER Department of Applied Physics, University of Hull, Hull, HU6 7RX. UK Abstract
The availability of single crystals of some of the rare earth transition metal compounds has allowed more detailed studies of the elastic and magnetoelastic effects in these materials [l]. Recent developments in this field will be reviewed with particular emphasis on the RCo2, RFez and RCos compounds. The very large magnetostrictive effects observed in the former two series are reflected in anomalous changes in their elastic properties. Measurements on two compounds will be described in detail. The elastic constants of the cubic Laves phase compound HoCo* have been measured as a function of temperature and magnetic field covering both the initial ferrimagnetic ordering at 78 K and the rotation of the magnetic easy direction from [loo] to [llO] below 16 K [2]. Dramatic softening of acoustic modes is observed in both of these
0378-4363/S3/0000~000/$03.00
@ 1983 North-Holland
temperature regions. Preliminary measurements will also be presented of the temperature dependence of the elastic constants of NdCoS, where there is particular interest in the rotation of the easy direction of magnetisation. NdCoS which is hexagonal has a magnetic easy hexagonal c-axis at room temperature. Below 290 K the moments move away from the c-axis until at 240 K they are confined to the basal plane. An inspection of earlier work on Gd would indicate strong magnetoelastic interactions in this region.
References B. Butler, D. Givord, F. Givord and S.B. Palmer, J. Phys. Cl3 (1980) L743. [2] B. Butler, D. Givord, F. Givord and S.B. Palmer, J. Phys. C, to be published. [I]
ELASTIC METAL
CONSTANT
MEASUREMENTS
OF RARE
EARTH
TRANSITION
COMPOUNDS
S.B. PALMER Department of Applied Physics, University of Hull, Hull, HU6 7RX. UK Abstract
The availability of single crystals of some of the rare earth transition metal compounds has allowed more detailed studies of the elastic and magnetoelastic effects in these materials [l]. Recent developments in this field will be reviewed with particular emphasis on the RCo2, RFez and RCos compounds. The very large magnetostrictive effects observed in the former two series are reflected in anomalous changes in their elastic properties. Measurements on two compounds will be described in detail. The elastic constants of the cubic Laves phase compound HoCo* have been measured as a function of temperature and magnetic field covering both the initial ferrimagnetic ordering at 78 K and the rotation of the magnetic easy direction from [loo] to [llO] below 16 K [2]. Dramatic softening of acoustic modes is observed in both of these
0378-4363/S3/0000~000/$03.00
@ 1983 North-Holland
temperature regions. Preliminary measurements will also be presented of the temperature dependence of the elastic constants of NdCoS, where there is particular interest in the rotation of the easy direction of magnetisation. NdCoS which is hexagonal has a magnetic easy hexagonal c-axis at room temperature. Below 290 K the moments move away from the c-axis until at 240 K they are confined to the basal plane. An inspection of earlier work on Gd would indicate strong magnetoelastic interactions in this region.
References B. Butler, D. Givord, F. Givord and S.B. Palmer, J. Phys. Cl3 (1980) L743. [2] B. Butler, D. Givord, F. Givord and S.B. Palmer, J. Phys. C, to be published. [I]