J. magn. magn. mater. J. magn. magn. mater. Co5/3Nb1/3BO4: A new cobalt oxyborate with a complex magnetic structure Kazak NV Belskaya NA Moshkina EM Bezmaternykh LN Vasiliev AD Bartolome J Arauzo A Universidad de Zaragoza Velikanov DA Gavrilkin SY Gorev MV Patrin GS Ovchinnikov SG 2021 research-article