TY - JOUR
T1 - Charge-density-wave order and multiple magnetic transitions in divalent Europium compound EuAl4
AU - Kaneko, Koji
AU - Kawasaki, Takuro
AU - Nakamura, Ai
AU - Munakata, Koji
AU - Nakao, Akiko
AU - Hanashima, Takayasu
AU - Kiyanagi, Ryoji
AU - Ohhara, Takashi
AU - Hedo, Masato
AU - Nakama, Takao
AU - Ōnuki, Yoshichika
N1 - Funding Information:
Acknowledgment We would like to thank M. Yogi, H. Niki, Y. Tokunaga, Y. Homma, S.-i. Fujimori, and H. Yamagami for valuable discussions. We also thank N. Aso for collaboration in the neutron scattering experiment on the related compound EuGa4. This work was partly supported by Grants-in-Aid for Scientific Research (C) (Nos. 24540336, 26400348, and 16K05031) and (B) (No. 20H01864) from the Japan Society for the Promotion of Science. The neutron diffraction experiment on SENJU at MLF J-PARC was performed under a user program (Proposal No. 2014A0080).
Publisher Copyright:
©2021 The Physical Society of Japan
PY - 2021/6/15
Y1 - 2021/6/15
N2 - Multiple transition phenomena in divalent Eu compound EuAl4 with the tetragonal structure were investigated via the single-crystal time-of-flight neutron Laue technique. At 30.0 K below a charge-density-wave (CDW) transition temperature of TCDW = 140 K, superlattice peaks emerge near nuclear Bragg peaks described by an ordering vector qCDW ¼ ð0; 0; δcÞ with δc ∼ 0.19. In contrast, magnetic peaks appear at q2 ¼ ðδ2; δ2; 0Þ with δ2 = 0.085 in a magnetic-ordered phase at 13.5 K below TN1 = 15.4 K. By further cooling to below TN3 = 12.2 K, the magnetic ordering vector changes into q1 ¼ ðδ1; 0; 0Þ with δ1 = 0.17 at 11.5 K and slightly shifts to δ1 = 0.194 at 4.3 K. No distinct change in the magnetic Bragg peak was detected at TN2 = 13.2 K and TN4 = 10.0 K. The structural modulation below TCDW with qCDW is characterized by the absence of the superlattice peak in the (0 0 l) axis. As a similar CDW transition was observed in SrAl4, the structural modulation with qCDW could be mainly ascribed to the displacement of Al ions within the tetragonal ab-plane. Complex magnetic transitions are in stark contrast to a simple collinear magnetic structure in isovalent EuGa4. This could stem from different electronic structures with the CDW transition between two compounds.
AB - Multiple transition phenomena in divalent Eu compound EuAl4 with the tetragonal structure were investigated via the single-crystal time-of-flight neutron Laue technique. At 30.0 K below a charge-density-wave (CDW) transition temperature of TCDW = 140 K, superlattice peaks emerge near nuclear Bragg peaks described by an ordering vector qCDW ¼ ð0; 0; δcÞ with δc ∼ 0.19. In contrast, magnetic peaks appear at q2 ¼ ðδ2; δ2; 0Þ with δ2 = 0.085 in a magnetic-ordered phase at 13.5 K below TN1 = 15.4 K. By further cooling to below TN3 = 12.2 K, the magnetic ordering vector changes into q1 ¼ ðδ1; 0; 0Þ with δ1 = 0.17 at 11.5 K and slightly shifts to δ1 = 0.194 at 4.3 K. No distinct change in the magnetic Bragg peak was detected at TN2 = 13.2 K and TN4 = 10.0 K. The structural modulation below TCDW with qCDW is characterized by the absence of the superlattice peak in the (0 0 l) axis. As a similar CDW transition was observed in SrAl4, the structural modulation with qCDW could be mainly ascribed to the displacement of Al ions within the tetragonal ab-plane. Complex magnetic transitions are in stark contrast to a simple collinear magnetic structure in isovalent EuGa4. This could stem from different electronic structures with the CDW transition between two compounds.
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U2 - 10.7566/JPSJ.90.064704
DO - 10.7566/JPSJ.90.064704
M3 - Article
AN - SCOPUS:85106360629
VL - 90
JO - Journal of the Physical Society of Japan
JF - Journal of the Physical Society of Japan
SN - 0031-9015
IS - 6
M1 - 064704
ER -