Elastic properties of PrxLa1−xFe4P12 in magnetic fields

The elastic properties of the filled skutterudite compound Pr x La 1-x Fe 4 P 12 for x = 0.95 and 0.85 have been investigated in magnetic fields by means of ultrasonic measurements. The elastic constant C 11 shows a softening towards low temperatures for both x = 0.95 and 0.85. The observed elastic softening in C 11 for x = 0.85 is gradually suppressed by increasing the applied field. The results for x = 0.85 is well reproduced qualitatively in terms of the quadrupolar susceptibility based on the crystalline electric field level scheme with Γ 3 non-Kramers doublet. However, C 11 for x = 0.95 shows unexpected behavior in applied field. We discuss the obtained field dependence of elastic constants of Pr x La 1-x Fe 4 P 12 for x = 0.95 and 0.85 from the viewpoints of the low-lying state of 4f-levels in Pr ions.