Acoustopiezomagnetism and the elastic moduli of CoF2

The piezomagnetic response of single crystal CoF2 is studied using acoustic oscillations at frequencies of similar to 55 MHz. Without an external magnetic field the results reproduce the data from direct static measurements. A magnetic field opens up an additional piezomagnetic response channel with an amplitude that is linear in the field strength. The efficiencies of the two channels become equal in the antiferromagnetic state for H similar to 3 T. Above the Neel temperature the mechanism for the first channel ceases to operate, while the piezomagnetic response associated with the new channel falls off approximately exponentially. The sound speeds for the different crystallographic directions are measured and the components of the elastic modulus tensor are calculated. (C) 2014 AIP Publishing LLC.