Neutron-diffraction studies of the nuclear magnetic phase diagram of copper

• Published in: Physical review. B, Condensed matter Vol. 45; no. 14; pp. 7772 - 7788
• Main Authors: ANNILA, A. J, CLAUSEN, K. N, OJA, A. S, TUORINIEMI, J. T, WEINFURTER, H
• Format: Journal Article
• Language: English
• Published: Woodbury, NY American Physical Society 01-04-1992; American Institute of Physics
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Physics; FCC crystals; Magnetization; Neutron diffraction; Bragg diffraction; Spontaneous; Antiferromagnetic materials; Brillouin zone; Magnetic phase diagram; Transition metal; Experimental study; Time variation; Magnetic susceptibility; Magnetic transition; Magnetic order; Copper; Magnetic field; Demagnetization; Sublattice; Symmetry
• ISSN: 0163-1829; 1095-3795
• DOI: 10.1103/PhysRevB.45.7772

The spontaneous antiferromagnetic (AF) order in the nuclear spin system of Cu was studied by use of neutron-diffraction experiments at nk temperatures. Copper is an ideal model system as a nearest-neighbor-dominated spin-3/2 fcc antiferromagnet. The phase diagram has been investigated by measuring the magnetic-field dependence of the (100) reflection, characteristic of a type-I AF structure, and of a Bragg peak at (02/3 2/3). The results suggest the presence of high-field (100) phases at 0.12 < = B < = B sub c approx 0.26 mT, for B along either the \100\ or \011\ crystalline axes, intermediate-field (02/3 2/3) structures around B = 0.09 mT for all field directions, and a zero-field (100) phase. No reflection corresponding to a high-field phase for B||\111\ has been found. the phase transition between the high-field phase and the intermediate-field structure is of first order. the change from (02/3 2/3) at intermediate fields to (100) at zero field is associated with a large region (0.02 < = B < = 0.06 mT) of coexisting-(100) and (02/3 2/3)-type Bragg peaks, and can be interpreted as either a two-phase region with a first-order transition at approx 0.06 mT and huge hysteresis effects or a single multiple-k phase which continuously transforms from being determined by (02/3 2/3) at approx 0.1 mT and (100) at zero field. The neutron-diffraction data have been compared with results of earlier susceptibility measurements to identify the translational periods of the three previously found antiferromagnetic phases for B||\100\. Recent theoretical work has yielded results in agreement with the experimental data.