Modulated Magnetism and Anomalous Electronic Transport in Ce3Cu4As4O2
Jiakui K. Wang, Shan Wu, Yiming Qiu, Jose Rodriguez Rivera, Qingzhen Huang, Collin L. Broholm, E. Morosan
The complex magnetism and transport properties of tetragonal Ce3Cu4As4O2 were examined through neutron scattering and physical properties measurements on polycrystalline samples. We find a lamellar structure consisting of alternating layers of CeCu4As4 with a single square Ce lattice and oxygen-linked Ce bi-layer Ce2O2. Extending along c, a tube-like Fermi surface from DFT calculations points to a quasi-two-dimensional electronic system. Peaks in the specific heat at the Neel temperature TN = 23.5 K and subsequent magnetic transitions at T2 = 15.8 K, and T3 = 1.9 K indicate three magnetic phase transitions or distinct cross-over phenomena. For TN neutron diffraction indicates the development of ferromagnetic ab sheets for both Ce sites, with alternating polarization along c, a wave vector K1=c, and a correlation length in excess of 50 A. For T2, the quasi-two-dimensional low-energy spin fluctuations with K2 = 1/2A and polarized perpendicular to K2 are suppressed. The data are consistent with quasi-two-dimensional antiferromagnetic order in the CeCu4As4 planes polarized along the k2 wave vector. T3 marks a spin-flop transition where the k1 staggered magnetization switches to in-plane polarization. While the narrow 4f bands lie deep below the Fermi surface, there are significant transport anomalies associated with the transitions; in particular a substantial reduction in resistivity for T2. At T = 100 mK the k1 modulated staggered moment is 0.85 υB saturation magnetization achieved for H = 7 T at T =2 K. We suggest that the unusual sequence of magnetic transitions may result from competing interactions and anisotropies for the two rare earth sites.
Magnetic materials, Neutron scattering, quantum criticallity, superconductivity.
, Wu, S.
, Qiu, Y.
, Rodriguez Rivera, J.
, Huang, Q.
, Broholm, C.
and Morosan, E.
Modulated Magnetism and Anomalous Electronic Transport in Ce<sub>3</sub>Cu<sub>4</sub>As<sub>4</sub>O<sub>2</sub>, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918417
(Accessed November 29, 2023)