Neutron scattering study on CeAgAs2

• Published in: Journal of magnetism and magnetic materials Vol. 324; no. 6; pp. 1157 - 1164
• Main Authors: Doert, Th, Schneidewind, A., Hölzel, M., Stockert, O., Rutzinger, D., Ruck, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2012; Elsevier
• Subjects: CeAgAs2; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetic structure; Metamagnetic transition; Neutron diffraction; Physics; Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.); Magnetic structure; Neutron diffraction; Metamagnetic transition; CeAgAs2; Antiferromagnetism; External fields; Silver Cerium Arsenides Mixed; Magnetic field effects; Lattice parameters; Neutron diffusion; Pnictides; Metamagnetism; Superstructure; CeAgAs; Ferromagnetism
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2011.11.001

CeAgAs2, an HfCuSi2 like layered pnictide, orders antiferromagnetically at TN=6.2(1)K. The ordering process was monitored in neutron diffraction experiments in the temperature range 10K≥T≥3.5K. At T=4K the lattice parameters are a=5.7438(1) Å, b=5.7696(1) Å and c=21.0067(2) Å. The diffraction pattern of the antiferromagnetic phase with a propagation vector k=[0,0,0] point towards ferromagnetically ordered moments in Ce layers stacked along [001], the individual layers are coupled antiferromagnetically with a +− −+type sequence. The alignment of moments within the Ce layers cannot be determined reliably from the experimental data so that two different structure models are discussed. The proposed metamagnetic transition was confirmed by diffraction experiments applying an external magnetic field at T<TN. In the interval 4K≤T≤6K, a relatively small field of μ0H≈0.3T suffices to fully suppress the antiferromagnetic ordering. The effect is completely reversible yet subject to hysteresis: After switching off the external field at any T<TN the magnetic reflections gain their original intensity within several 10min indicating the restoring of the antiferromagnetic phase. ► The magnetic ordering of CeAgAs2 was monitored by neutron data between 10°K and 3.75°K. ► CeAgAs2 orders antiferromagnetic below TN=6.2(1)K. ► Possible models of the antiferromagnetic structure are discussed. ► A metamagnetic transition by applying an external field was confirmed and found fully reversible.