Spin colossal magnetoresistance in an antiferromagnetic insulator

Qiu, Z.*; Hou, D.*; Barker, J.*; Yamamoto, Kei; Gomonay, O.*; Saito, Eiji*

Nature Materials, 17(7), p.577 - 580, 2018/05

https://doi.org/10.1038/s41563-018-0087-4

Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal-insulator transition. CMR occurs due to a correlation between the magnetic structure and electron conduction and has inspired extensive studies for decades. Here, in the antiferromagnetic insulator CrO, we found a sharp transition between conducting and nonconducting states for spin currents at room temperature. The spin-current transmission changes by two orders of magnitude within a narrow temperature window of 14K around the Neel temperature. The spin conductor-nonconductor transition can be modulated by a magnetic field, giving an isothermal change of spin-current transmission of up to 500%, effectively an on-off switch for spin currents.

Fabrication and magnetic control of YFeO cantilevers

Seo, Y.-J.*; Harii, Kazuya; Takahashi, Ryo*; Chudo, Hiroyuki; Oyanagi, Koichi*; Qiu, Z.*; Ono, Takahito*; Shiomi, Yuki*; Saito, Eiji

Applied Physics Letters, 110(13), p.132409_1 - 132409_4, 2017/03

https://doi.org/10.1063/1.4979553

We have fabricated ferrite cantilevers in which their vibrational properties can be controlled by external magnetic fields. Submicron-scale cantilever structures were made from YFeO films by physical etching combined with the use of a focused ion beam milling technique. We found that the cantilevers exhibit two resonance modes which correspond to horizontal and vertical vibrations. Under external magnetic fields, the resonance frequency of the horizontal mode increases, while that of the vertical mode decreases, quantitatively consistent with our numerical simulation for magnetic forces. The changes in resonance frequencies with magnetic fields reach a few percent, showing that an efficient magnetic control of resonance frequencies was achieved.

Origin of the spin Seebeck effect in compensated ferrimagnets

Geprgs, S.*; Kehlberger, A.*; Coletta, F.*; Qiu, Z.*; Guo, E.-J.*; Schulz, T.*; Mix, C.*; Meyer, S.*; Kamra, A.*; Althammer, M.*; et al.

Nature Communications (Internet), 7, p.10452_1 - 10452_6, 2016/02

https://doi.org/10.1038/ncomms10452

Spin current generation from sputtered YFeO films

Lustikova, J.*; Shiomi, Yuki*; Qiu, Z.*; Kikkawa, Takashi*; Iguchi, Ryo*; Uchida, Kenichi*; Saito, Eiji

Journal of Applied Physics, 116(15), p.153902_1 - 053902_6, 2014/10

https://doi.org/10.1063/1.4898161

Amphoteric ion exchange membrane synthesized by radiation-induced graft copolymerization of styrene and dimethylaminoethyl methacrylate into PVDF film for vanadium redox flow battery applications

Qiu, J.*; Zhang, J.*; Chen, J.; Peng, J.*; Xu, L.*; Zhai, M.*; Li, J.*; Wei, G.*

Journal of Membrane Science, 334(1-2), p.9 - 15, 2009/05

https://doi.org/10.1016/j.memsci.2009.02.009

Poly(vinylidene difluoride) (PVDF) film was grafted with styrene (St) and dimethylaminoethyl methacrylate (DMAEMA) using irradiation techniques. Through subsequent sulfonation and protonation processes, a new kind of amphoteric ion exchange membrane (AIEM) was synthesized. The grafting yield () increased with absorbed dose and leveled off at about 60 kGy. The properties of the AIEM strongly depended on the composition and of the film, i.e. higher content of DMAEMA brought lower permeability of vanadium ions and conductivity. Finally, an AIEM was assembled and tested in the vanadium redox flow battery (VRFB) system. It was found that the VRFB assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.2V after placed for 68h, which was much longer than that with the Nafion117 membrane. Therefore, this work provides a novel method to develop potential substitute of Nafion membranes to be applied in VRFB system.

How to start a network? Experience in networking and achievements of the IRPA Young Generation Network

Andresz, S.*; Betos, C.*; Ha, W.-H.*; Hamida, T.*; Hussain, B. S.*; Kabrt, F.*; Nusrat, O.*; Michaelidesova, A.*; Lima Thiago V. M.*; Movsisyan, N.*; et al.

no journal, , 

Since its establishment in 2018, the Young Generation Network (YGN) has been dedicated, with support of the International Radiation Protection Association (IRPA), to a variety of activities to promote communication, collaboration and professional development of students, young professionals and scientists in radiation protection and its allied fields. This presentation will first report on the activities performed from the middle of 2018 to 2022, with highlights on some important events, collaboration and publications. The discussion and insight obtained from each activity will be summarized and used to inform how the IRPA YGN will aim to achieve its on-going activities and continue to follow the ways paved in the Strategic Agenda 2022-2024 and despite the very specific challenges faced by a "young generation network". Namely, running international surveys (for example, on the usage of social media in radiation protection, or on the long-term consequences of the COVID-19 pandemic), engaging national YGNs (for example in contest and discussion about the future of the radiation protection profession), extending the network, finding new relationships with networks with an interest in the young generation and participation in (remote) events will be aspired for.