Pressure effect on successive magnetic transitions in a frustrated compound YbAgGe

We report the measurements of electrical resistivity ρ under various pressures for the single crystal of a heavy-fermion compound YbAgGe. This compound undergoes two magnetic phase transitions at TM1=0.8K (second order) and TM2=0.65K (first order). With applying pressure above 0.5GPa, the resistive anomalies at TM1 and TM2 merge into a sharp drop at TM. In the range 0.51.5GPa, ρ(0.5K) largely decreases and the anomaly in ρ(T=TM) becomes broader and shifts to higher temperatures. These significant changes at 1.5GPa suggest a transition from a small-moment ordered state to a stable magnetic state with suppressed spin fluctuations