A series of Sr(Co1-xNix)2As2 single crystals was synthesized, allowing a comprehensive phase diagram with respect to field, temperature, and chemical substitution to be established. Our neutron diffraction experiments revealed a helimagnetic order with magnetic moments ferromagnetically aligned in the ab plane and a helimagnetic wave vector of q=(0,0,0.56) for x=0.1. The combination of neutron diffraction and angle-resolved photoemission spectroscopy measurements shows that the tuning of a flat band with dx2-y2 orbital character drives the helimagnetism and indicates the possibility of a quantum order-by-disorder mechanism.
Publication Source (Journal or Book title)
Physical Review B
Li, Y., Liu, Z., Xu, Z., Song, Y., Huang, Y., Shen, D., Ma, N., Li, A., Chi, S., Frontzek, M., Cao, H., Huang, Q., Wang, W., Xie, Y., Zhang, R., Rong, Y., Shelton, W., Young, D., Ditusa, J., & Dai, P. (2019). Flat-band magnetism and helical magnetic order in Ni-doped SrCo2As2. Physical Review B, 100 (9) https://doi.org/10.1103/PhysRevB.100.094446