Magnetization and transport measurements have been performed to study the martensitic and pre-martensitic transitions for a series of ferromagnetic Heusler alloys. Both magnetization and resistivity measurements show a clear jump at the martensitic transition and a discontinuous slope change at the pre-martensitic transition. The characteristic temperatures correspond well with those derived from previous direct structural results from neutron scattering, electron microscopy and ultrasonic studies. The martensitic transition temperature decreases with increasing Mn concentration.

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The generation and attenuation of phonons at ferromagnetic resonance has been studied both theoretically and experimentally. We have observed for the first time the effect of resonant reabsorption of phonons propagating through thick Ni films. The predictions of the theory are in very good agreement with experiment.

Sound transmission experiments on single-crystal and polycrystalline nickel and iron samples 10–20 μm thick demonstrate an amplitude dependence on conductivity indicative of an electron damping effect. The samples form part of the common wall between two microwave cavities. Transverse sound waves were generated via magnetostriction with a static magnetic field perpendicular to the sample surface and perpendicular to the incident microwave magnetic field. Longitudinal sound waves were generated by direct electromagnetic excitation with a static magnetic field parallel to the sample surface and parallel to the incident microwave magnetic field. An exponential dependence of transmitted sound amplitude versus sample conductivity was observed as the temperature was varied. This exponential amplitude dependence on conductivity is what is expected from theories for sound wave attenuation in metals. For our samples this attenuation coefficient is of the order of 0.5 dB/μm. At low temperatures, where the product of the sound propagation constant and the electron mean free path approaches and exceeds unity, a decrease in the sound amplitude dependence on conductivity was observed, also in agreement with theory.

Magnetization studies on organic single-crystal superconductors of κ-(BEDT-TTF)2Cu[N(CN)2]Br with the field H parallel to the b axis (perpendicular to the conducting plane) show anomalous field and temperature dependence of vortex pinning in the mixed state. At high temperatures, the magnetization M decays with increasing field with a power-law dependence. The normalized relaxation rate S=d(ln M)/d(ln t) decreases monotonically with H. At low temperatures (T<7 K), a change of sign in the curvature of M(H) is observed, accompanied by a corresponding change in S as a function of H. Measurement of the irreversibility field Hrev shows a universal power-law dependence of Hrev on (1−T/Tc) in the temperature range investigated. We suggest that the magnetic anomaly observed is due to a dimensional crossover in the nature of vortex pinning.