Pressure-dependent spin fluctuations and magnetic structure in the topologically frustrated spin glass alloy Y(Mn0.95Al0.05)2

Abstract

Longitudinal field (LF = 110 G) muon spin relaxation (mu SR) has been used to investigate the pressure dependence (P < 4.5 kbar) of paramagnetic spin fluctuations in the spin glass alloy Y(Mn0.95Al0.05)(2) via observation of the mu(+) spin depolarization. External mechanical force is seen to counteract the Al-induced chemical pressure, fully delocalizing the Mn moment and altering the nature of the spin fluctuation spectrum sensed by the muon. A qualitative change in the functional form of the mu(+) spin depolarization is observed. Complementary ambient and high-pressure neutron diffraction measurements suggest not only pressure-dependent structural transitions but also the instability of the localized manganese moment. The ambient and high-pressure mu(+) spin depolarization results from Y(Mn0.95Al0.05)(2) are likened to P = 0 results reported for other Y(Mn1-xAlx)(2) alloys. Finally, the possibility of using mu(+) spin depolarization rates to predict experimental inelastic neutron scattering (INS) line widths is considered; the muon having the potential to provide information equivalent to that obtained via INS but with greatly reduced data collection times.