CONDENSED MATTER

A$_1$–A$_2$ splitting in pure $^3$He in nematic aerogel

V. V. Dmitriev^a, M. S. Kutuzov^b, D. V. Petrova^ca, A. A. Soldatov^a, A. N. Yudin<sup>a

a</sup> P.L. Kapitza Institute for Physical Problems of Russian Academy of Sciences, 119334 Moscow, Russia
^b Metallurg Engineering Ltd., 11415 Tallinn, Estonia
^c National Research University Higher School of Economics University, 101000 Moscow, Russia

Abstract: Here, we present the results of vibrating wire experiments in pure $^3$He (without $^4$He coverage) in nematic aerogel. We investigated the dependence of splitting of the superfluid transition temperature of $^3$He in aerogel on magnetic field. In addition to our previous work, we used a wider range of magnetic fields (up to 31 kOe) and managed to detect both the “upper” and “lower” superfluid transition temperatures. The solid paramagnetic $^3$He layer on the aerogel strands activates the magnetic scattering channel. According to theory, it should result in linear splitting at high ($\ge20$ kOe) fields, while at lower fields the splitting is expected to be nonlinear. We were able to observe this nonlinearity, but we have a discrepancy with theoretical predictions regarding the range of fields where nonlinearity occurs. Possible reasons for this are discussed.

Received: 26.07.2025
Revised: 03.09.2025
Accepted: 03.09.2025

Language: English

DOI: 10.31857/S0370274X25100088