Abstract
The discovery of pressure-induced superconductivity in helimagnets (CrAs, MnP) has attracted considerable interest in understanding the relationship between complex magnetism and unconventional superconductivity. However, the nature of the magnetism and magnetic interactions that drive the unusual double-helical magnetic order in these materials remains unclear. Here, we report neutron scattering measurements of magnetic excitations in CrAs single crystals at ambient pressure. Our experiments reveal well defined spin wave excitations up to about 150 meV with a pseudogap below 7 meV, which can be effectively described by the Heisenberg model with nearest neighbor exchange interactions. Most surprisingly, the spin excitations are largely quenched above the Néel temperature, in contrast to cuprates and iron pnictides where the spectral weight is mostly preserved in the paramagnetic state. Our results suggest that the helimagnetic order is driven by strongly frustrated exchange interactions, and that CrAs is at the verge of itinerant and correlation-induced localized states, which is therefore highly pressure-tunable and favorable for superconductivity.
| Original language | English |
|---|---|
| Article number | 127501 |
| Journal | Chinese Physics Letters |
| Volume | 39 |
| Issue number | 12 |
| DOIs | |
| State | Published - Nov 1 2022 |
| Externally published | Yes |
Funding
This work was supported by the National Natural Science Foundation of China (Grant No. 11874119), and Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01). The datasets for the inelastic neutron scattering experiment on the MAPS chopper spectrometer are available from the ISIS facility, Rutherford Appleton Laboratory data portal (10.5286/ISIS.E.RB1510119). The neutron data taken at the NCNR are available at ftp://ftp.ncnr.nist.gov/pub/ncnrdata. All other data that support the plots within this work and other findings in this study are available from the corresponding authors upon reasonable request.