Superfluid transition to ABM state of 3He in aerogel

Abstract

Stability of the ABM pairing state in aerogel is studied in order to identify the equal-spin pairing (ESP) state of superfluid 3He there close to the transition temperature T c( P). It is shown by examining T c( P) beyond the mean-field approximation that the quenched disorder makes the normal to ABM transition point higher compared with that of the normal to BW transition over a wider pressure range than in the bulk case. If the ESP state in 3He in aerogel is the ABM state, the present result naturally explains why the ESP state in aerogel at least upon cooling is realized even at lower pressures than the so-called PCP in the bulk case.