Keun Jenn Sun

The effect of Fe-Ni films on the insertion loss of saw

Abstract The insertion loss of 618 MHz quartz SAW delay lines with nickel-rich Fe-Ni alloy films deposited between the interdigital electrodes exhibits as large a response to an applied magnetic field as that observed with pure nickel films. In addition, the alloys exhibit an enhanced domain wall motion effect.

Ultrasonic attenuation measurements on Er1−xHoxRh4B4

Abstract Ultrasonic attenuation measurements have been performed in the superconducting, paramagnetic, and ferromagnetic states of polycrystalline samples of Er 1− x Ho x Rh 4 B 4 with x =0.6, 0.813 and 0.912, as a function of temperature at constant applied magnetic fields and at constant temperatures up to fields of 7 kOe. For the two samples that exhibit superconductivity, the temperature dependent attenuation curve showed a relative minimum at the superconducting transition temperature T c1 , then increased in the superconducting state with a step decrease at T m . The sample, with x =0.912 ferromagnetically ordered without passing through the superconducting state, had a relative minimum in attenuation at T m , then its attenuation increased as the temperature was lowered. It may be possible that the crystalline electric field (CEF) suppresses that interaction between the spin fluctuations which are associated with the ferromagnetic transition and the phonons. Superconducting currents may screen the effect of the CEF and allow the interaction to appear in the superconducting state.

Ultrasonic Investigation of Novel Superconducting Systems

Ultrasonic attenuation measurements are reported for the superconducting, normal, and mixed states of the heavy Fermion superconductors UPt3 and URu2Si2 and in the alloys of the ternary superconductors Er1-x HoxRh4B4. A peak in attenuation in the mixed state of UPt3 may be indicative of collective excitations of the flux line lattice. A broad maximum in attenuation is found below the superconducting transition temperature of URu2Si2. An increase in attenuation in the superconducting phase of the reentrant ternary superconductors with x = 0.6 and 0.813 is ascribed to increased spin phonon interaction induced by superconducting screening of crystalline electric fields.