Transition-metal oxides with an ABO 3 perovskite structure exhibit strongly entangled structural and electronic degrees of freedom and thus, one expects to unveil exotic phases and properties by acting on the lattice through various external stimuli. Using the Jahn-Teller active praseodymium vanadate Pr 3+ V 3+ O 3 compound as a model system, we show that PrVO 3 Néel temperature T N can be raised by 40 K with respect to the bulk when grown as thin films. Using advanced experimental techniques, this enhancement is unambiguously ascribed to a tetragonality resulting from the epitaxial compressive strain experienced by the films. First-principles simulations not only confirm experimental results, but they also reveal that the strain promotes an unprecedented orbital-ordering of the V 3+ d electrons, strongly favoring antiferromagnetic interactions. These results show that an accurate control of structural aspects is the key for unveiling unexpected phases in oxides.T oo . It produces a G-type orbital-ordering with alternating occupancy of the d xz and d yz orbitals on neighboring V sites according to a rock-salt like pattern -the second electron is located in the low energy d xy orbital on all V sites. It is then followed by a magnetic transition at T N
Strain engineering is an important issue in oxides thin lms to explore new functionalities. Here, a series of high quality epitaxial PrVO 3 (PVO) thin lms were grown, by Pulsed Laser Deposition (PLD) technique, as a function of thickness on (La,Sr)(Al,Ta)O 3 (100) [LSAT (100)] and LaAlO 3 (100) [LAO (100)] substrates with nominal lattice mismatch of-0.8 % and-2.9 %, respectively. The X-ray diraction revealed a constant out-of-plane lattice parameter of PVO/LSAT with increase in lm thickness, while a rather continuous decrease for PVO/LAO lms. Whereas thicker PVO lms show a ferromagnetic-like behavior, at low thickness a surprising decrease of coercivity (H c) and increase of saturation magnetization (M s) is observed. This behavior is described using a classical model of dead layer which possesses a strong paramagnetic susceptibility. It is also shown how capping of PVO lm can aid in recovering the pure magnetic properties of PVO, by diminishing the contribution from dead layer. Finally, the Néel temperature (T N) is examined as a function of lm thickness, and found to vary in the range of 25 K and 30 K for LSAT and LAO, respectively. These results pave the way for the use of vanadate in thin lm devices.
We have probed the structural and magnetic properties of PrVO 3 (PVO) thin lms grown on the (001)-, ( 110)-and ( 111)-oriented SrTiO 3 (STO) substrates. By changing the substrate orientation,(1) the out-of-plane orientation of lm can be tuned to [110], [100] / [010], and [011] / [311], (2) the number of crystal variants in the lm can be varied, for ex. we observe single domain lm on (110)oriented STO, whereas two domains in the lm grown on the (111)-oriented STO substrate. The lattice strain induced by using dierent oriented substrates has direct inuence on the magnetic properties of PVO lms. The magnetic moment of PVO lms radically enhances from 0.4 µ B /f.u. for STO (001) to 2.3 µ B /f.u. for STO (111). While, lms on (001)-oriented STO substrate display out-of-plane anisotropy, an in-plane anisotropy is observed for lms grown on the (110)-and (111)-oriented STO substrates. In addition, a strong uniaxial magnetic anisotropy is also extracted for a partially relaxed lm on the (110)-oriented STO substrate. Such ndings can help oxide community in the better understanding of magnetic anisotropy in vanadate thin lms, a subject that still lacks scientic investigations.
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