title: Hard magnetic ferrite with a gigantic coercivity and high frequency millimetre wave rotation.
abstract: Magnetic ferrites such as Fe(3)O(4) and Fe(2)O(3) are extensively used in a range of applications because they are inexpensive and chemically stable. Here we show that rhodium-substituted ε-Fe(2)O(3), ε-Rh(x)Fe(2-x)O(3) nanomagnets prepared by a nanoscale chemical synthesis using mesoporous silica as a template, exhibit a huge coercive field (H(c)) of 27 kOe at room temperature. Furthermore, a crystallographically oriented sample recorded an H(c) value of 31 kOe, which is the largest value among metal-oxide-based magnets and is comparable to those of rare-earth magnets. In addition, ε-Rh(x)Fe(2-x)O(3) shows high frequency millimetre wave absorption up to 209 GHz. ε-Rh(0.14)Fe(1.86)O(3) exhibits a rotation of the polarization plane of the propagated millimetre wave at 220 GHz, which is one of the promising carrier frequencies (the window of air) for millimetre wave wireless communications.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo                 113-0033, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Namai
authors.forename: Marie
authors.initials: M
authors.lastname: Yoshikiyo
authors.forename: Kana
authors.initials: K
authors.lastname: Yamada
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Sakurai
authors.forename: Takashi
authors.initials: T
authors.lastname: Goto
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yoshida
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakajima
authors.forename: Tohru
authors.initials: T
authors.lastname: Suemoto
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tokoro
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Ohkoshi