\muSR-dtected Soft mode toward a Possible Phase Transition in disordered spin gap system (CH3)2CHNH3-Cu(ClxBr1-x)3

Abstract

Measurements of macroscopic properties have indicated that the bond-disordered spin-gap system (CH3)2CHNH3-Cu(ClxBr1-x)3 is gapless when x is between 0.44 and 0.87. Using muon spin relaxation to investigate microscopic properties of sample with x=0.35, we observed a dynamical spin fluctuation, whose characteristic frequency decreases with decreasing temperature, indicating a magnetic ground state.Comment: 4 pages. Submitted to muSR2008(Tsukuba) and accepted for publicatio