Magnetic and transport properties, and electronic structure of the layered chalcogenide AgCrSe2

We report a detailed study of the magnetic and transport properties of polycrystalline A-CrSe2, a layered magnetic chalcogenide that orders antiferromagnetically without frustration at 55 K. The magnetic ordering corresponds to ill-plane ferromagnetic interactions with anti ferromagnetic coupling between the planes. Transport studies suggest a semiconductor that is at the I-M transition boundary in terms of its resistivity, with variable-range hopping behavior at intermediate temperatures and Efros-Shklovskii hopping at low temperatures. At high temperatures (>340 K) the temperature coefficient of resistance turns positive as a result, we believe, of disorder in the silver sub-lattice. First principles density functional calculations of the electronic structure suggest a magnetic insulator ground state, and means to tune the system to ferromagnetic half-metal. (C) 2002 Elsevier Science Ltd. All rights reserved.