We measured the pressure dependence of the complex transverse acoustic impedance of superfluid 3He-B
using an AC-cut quartz transducer. The measurements were performed by a CW bridge method at the third harmonics of
the fundamental resonance frequency 9.56 MHz. We obtained the real (Z') and the imaginary (Z'') parts of the transverse
acoustic impedance independently. Z' and Z'' did not change from the normal state values at Tc, but Z' started to increase
at the pair breaking edge temperature Tpb upon cooling. The slope of the increase changed at a temperature defined as T*
which was lower than Tpb. With further cooling, it reached a maximum and then decreased slowly. Z'' had a small peak
at T* and decreased rapidly with decreasing temperature. These temperature dependences were possibly influenced by
quasi-particle density of states within the energy gap originating from the surface Andreev bound states. At lower
pressure the maximum of Z' and the small peak of Z'' moved to smaller T/Tc and became larger due to the pressure
dependence of the energy gap.
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