Abstract
Oxygen is the only elemental molecule which carries an electronic magnetic moment. As a consequence, the different solid phases encountered on cooling show various degrees of magnetic order, and similar behavior is expected under compression. Here we present neutron diffraction data which reveal the magnetic ordering under high pressure in the (“orange”) phase, i.e., in the range 6–8 GPa and 20–240 K. We show that contains in total three different magnetic structures, all of them being antiferromagnetic and differing in the stacking sequence of sheets along the axis. This structural diversity can be explained by the quasi-two-dimensional nature of and the strong orientation dependence of the magnetic exchange interaction between molecules. The results show that is a room temperature antiferromagnet.
- Received 15 January 2010
DOI:https://doi.org/10.1103/PhysRevLett.104.115501
©2010 American Physical Society
Synopsis
Pressed to order
Published 5 April 2010
High-pressure neutron diffraction reveals solid oxygen’s complex magnetic phase diagram.
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