Magnon spin transport in the van der Waals antiferromagnet CrPS4 for noncollinear and collinear magnetization

We investigate the injection, transport, and detection of magnon spins in the van der Waals antiferromagnet chromium thiophosphate (CrPS4). We electrically and thermally inject magnon spins by platinum contacts and examine the nonlocal resistance as a function of in-plane magnetic field up to 12 Tesla. We observe a large nonlocal resistance from both the electrically and thermally excited magnon modes above the spin-flip field where CrPS4 is in the collinear state. At 25 K for an in-plane field of range 5-12 T, we extract the magnon relaxation length λm ranging 200-800nm and a typical magnon conductivity of σm≈1×104Sm-1, which is one order of magnitude smaller than in yttrium iron garnet (YIG) films at room temperature. Moreover, we find that σm is almost zero for CrPS4 in the noncollinear state. In addition the nonlocal spin Seebeck effect shows a complex behavior as a function of field. Our results open up the way to understanding the role of the antiferromagnetic magnon modes on spin injection into antiferromagnets and implementation of two-dimensional magnets for scalable magnonic circuits.