Element-specific observation of the ferromagnetic ordering process in UCoAl via soft X-ray magnetic circular dichroism
Takeda, Yukiharu
; Saito, Yuji
; Okane, Tetsuo
; Yamagami, Hiroshi; Matsuda, Tatsuma*; Yamamoto, Etsuji
; Haga, Yoshinori
; Onuki, Yoshichika*
We have performed soft X-ray magnetic circular dichroism (XMCD) experiments on the itinerant-electron metamagnet UCoAl at the U 4
-5
(
) and Co 2
-3
(
) absorption edges in order to investigate the magnetic properties of the U 5
and Co 3
electrons separately. From the line shape of the XMCD spectrum, it is deduced that the orbital magnetic moment of the Co 3
electrons is unusually large. Through the systematic temperature (
)- and magnetic field (
)-dependent XMCD measurements, we have obtained two types of the magnetization curve as a function of
and
(M-H curve and M-T curve, respectively). The metamagnetic transition from a paramagnetic state to a field-induced ferromagnetic state was observed clearly under 15 K at
. The value of the
and its
-dependence agree well between the U and Co sites, and the bulk magnetization. Whereas, we have discovered the remarkable differences in the M-H and M-T curves between the U and Co sites. The present findings show clearly that the role of the Co 3
electrons should be considered more carefully in order to understand the origin of the magnetic ordering in UCoAl.