Abstract
Neutron diffraction experiments have been carried out to characterize the magnetic structures and order parameters in an intermediate phase of NdB4 showing the successive phase transitions at TO = 17.2 K, TN1 = 7.0 K, and TN2 = 4.8 K. We have revealed the antiferromagnetic ordering with the propagation vectors q0 = (0,0,0) q0 and qS1 = δ δ 0:4) (δ ~ 0.14), and q0 and qs2 = (0:2; 0; 0:4) in phase II (Tn1 < T < To), phase III (Tn2 7lt; T < TN1), and phase IV (T < TN2), respectively. The observed patterns in phase II are successfully explained by postulating a coplanar structure with static magnetic moments in the tetragonal ab-plane. We have found that the magnetic structure in phase II can be uniquely determined to be a linear combination of antiferromagnetic "all-in=all-out"-type (∥4) and "vortex"-type (∥2) structures, consisting of a ∥4 main component (77%) with a small amplitude of ∥2 (23%). We propose that the quadrupolar interaction holds the key to stabilizing the noncollinear magnetic structure and quadrupolar order. Here, the frustration in the Shastry-Sutherland lattice would play an essential role in suppressing the dominance of the magnetic interaction.
| Original language | English |
|---|---|
| Article number | 044705 |
| Journal | Journal of the Physical Society of Japan |
| Volume | 86 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 15 2017 |
Funding
The neutron scattering experiment at Oak Ridge National Laboratory was supported in part by the U.S.-Japan Cooperative Program on Neutron Scattering. A portion of this research used resources at ORNL's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. This work was supported by a Grant-in-Aid for Scientific Research (C) (No. 25390133) from the Japan Society for the Promotion of Science.