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Unravelling the Elusive Antiferromagnetic Order in Wurtzite and Zinc Blende CoO Polymorph Nanoparticles
Author(s) -
Roca Alejandro G.,
Golosovsky Igor V.,
Winkler Elin,
LópezOrtega Alberto,
Estrader Marta,
Zysler Roberto D.,
Baró María Dolors,
Nogués Josep
Publication year - 2018
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201703963
Subject(s) - wurtzite crystal structure , antiferromagnetism , condensed matter physics , materials science , ferromagnetism , spins , zinc , crystallography , chemistry , physics , metallurgy
Although cubic rock salt‐CoO has been extensively studied, the magnetic properties of the main nanoscale CoO polymorphs (hexagonal wurtzite and cubic zinc blende structures) are rather poorly understood. Here, a detailed magnetic and neutron diffraction study on zinc blende and wurtzite CoO nanoparticles is presented. The zinc blende‐CoO phase is antiferromagnetic with a 3rd type structure in a face‐centered cubic lattice and a Néel temperature of T N (zinc‐blende) ≈225 K. Wurtzite‐CoO also presents an antiferromagnetic order, T N (wurtzite) ≈109 K, although much more complex, with a 2nd type order along the c ‐axis but an incommensurate order along the y ‐axis. Importantly, the overall magnetic properties are overwhelmed by the uncompensated spins, which confer the system a ferromagnetic‐like behavior even at room temperature.