1. Comparing magnetism in isostructural oxides A[sub](0.8)La[sub](1.2)MnO[sub](4.1) : anisotropic spin glass (A = Ba) versus long range order (A = Sr)Mirela Dragomir, Paul A. Dube, Iztok Arčon, Chad Boyer, Meghan Rutherford, Christopher Wiebe, Graham King, Hanna Dabkowska, John E. Greedan, 2019, izvirni znanstveni članek Opis: This study presents the strikingly distinct magnetic properties of two isostructural compounds, Ba0.8La1.2MnO4.1
and Sr0.8La1.2MnO4.1 (K2NiF4
type, I4/mmm). Spectroscopic studies have shown that Mn is in a +3.0(1) oxidation state only,
in both compounds; therefore, the charge is balanced by accommodating extra oxygen at interstitial sites, as confirmed by
neutron powder diffraction. We found that the Ba compound exhibits an exceedingly rare anisotropic spin glass behavior, Tg =
26.4(4) K, with the moment freezing along the c-axis only while the in-plane spin components remain dynamic well below Tg.
Experimental results including neutron diffraction, heat capacity, and magnetic (dc and ac) measurements performed on an
oriented single crystal support this conclusion. This is a remarkable result, the only other known example of an anisotropic spin
glass being Fe2TiO5. The spin glass state in Ba0.8La1.2MnO4.1 is argued to arise due to competing antiferromagnetic and
ferromagnetic 180° Mn3+−O−Mn3+ superexchange interactions. In contrast, the Sr analogue shows 2D antiferromagnetic
correlations and long-range antiferromagnetic order below 95(1) K with a remarkably reduced ordered moment of 1.449(49)
μB/Mn3+ instead of the ∼4 μB expected for an S = 2 ion.
Ključne besede: antiferomagnetiki, Mn XANES, struktura
Objavljeno v RUNG: 23.10.2019; Ogledov: 3718; Prenosov: 0
Gradivo ima več datotek! Več... |
