Direct observation of spontaneous weak ferromagnetism in the superconductor ErNi2B2C.
Neutron measurements show that superconducting ErNi2B2C (T(C) = 11 K) develops antiferromagnetic spin density wave magnetic order (T(N) = 6 K), which squares up with decreasing temperature yielding a series of higher-order magnetic Bragg peaks with odd harmonics. Below T(WFM) = 2.3 K where magnetization indicates a net moment develops, even-order Bragg peaks develop which low field (approximately 3 Oe) polarized beam measurements show are magnetic in origin. The data directly demonstrate the existence of a net magnetization with a periodicity of 20a, confirming the microscopic coexistence of spontaneous weak ferromagnetism with superconductivity.
Choi
S M
SM
National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Lynn
J W
JW
Lopez
D
D
Gammel
P L
PL
Canfield
P C
PC
Bud'ko
S L
SL