Materials 286KChris Freeze

M—I Transition In Rare-Earth Nickelates And The Impact Of Structural Distortions Outline: LaNiO 3 : The basics Tuning the Metal-Insulator Transition 1.Structural distortions 2.Oxygen deficiency 3.Dimensionality

Materials 286KChris Freeze LaNiO 3 Remember me?

Materials 286KChris Freeze LaNiO 3 Remember me?

Materials 286KChris Freeze Gou et al., Phys. Rev. B 84 (2011) LaNiO 3 : An Introduction Paramagnetic Correlated metal

Materials 286KChris Freeze LaNiO 3 : An Introduction Paramagnetic Correlated metal Sanchez et al., Phys. Rev. B 54 (1996) Sreedhar et al., Phys. Rev. B 46 (1992)

Materials 286KChris Freeze Rare earth size allows tuning structural distortions Varying A-site radius: LnNiO 3 Medarde et al., J. Phys. Condensed Matter 9 (1997) Problem: Hard to prepare…

Materials 286KChris Freeze Varying A-site radius: LnNiO 3 Structural distortions dictate the M–I transition of LnNiO 3 Torrance et al. Phys. Rev. B. 45 (1992) 8209–8212.

Materials 286KChris Freeze Measuring structural distortions with neutron diffraction Varying A-site radius: LnNiO 3 Garcia-Munoz et al., Phys. Rev. B 46 (1992)

Materials 286KChris Freeze Staub et al., Phys. Rev. Lett. 88 (2002) Charge ordering: 2 Ni 3+ -> Ni (3+δ)+ + Ni (3-δ’)+ Varying A-site radius: LnNiO 3 For NdNiO 3, δ+δ’ = 0.45 Smaller than bond-valence sum (0.6)

Materials 286KChris Freeze Obradors et al. Phys. Rev. B 47 (1993) Zhou et al., Phys. Rev. B 61 (2000) Pressure effects – alters oxygen vibration frequency Varying A-site radius: LnNiO 3 NdNiO 3 PrNiO 3 LaNiO 3 Sm 0.5 Nd 0.5 NiO 3

Materials 286KChris Freeze Medarde et al., Phys. Rev. Lett. 80 (1998) 2397–2400. Lattice dynamics (i.e. electron-lattice coupling) plays an important role Varying A-site radius: LnNiO 3

Materials 286KChris Freeze M—I Transition In Rare-Earth Nickelates And The Impact Of Structural Distortions Outline: LaNiO 3 : The basics Tuning the Metal-Insulator Transition 1.Structural distortions 2.Oxygen deficiency 3.Dimensionality

Materials 286KChris Freeze Sanchez et al., Phys. Rev. B 54 (1996) Qiao and Bi, Europhysics Lett. 93 (2011) Oxygen Deficiency: LaNiO 3-δ Metal-Insulator transition near δ = 0.25 LaNiO 2.84 LaNiO 2.64

Materials 286KChris Freeze Sanchez et al., Phys. Rev. B 96 (1996) Qiao and Bi, Europhysics Lett. 93 (2011) Oxygen Deficiency: LaNiO 3-δ r Ni3+ = 0.60 nm r Ni2+ = 0.69 nm LaNiO 2.75 LaNiO 2.5

Materials 286KChris Freeze M—I Transition In Rare-Earth Nickelates And The Impact Of Structural Distortions Outline: LaNiO 3 : The basics Tuning the Metal-Insulator Transition 1.Structural distortions 2.Oxygen deficiency 3.Dimensionality

Materials 286KChris Freeze Scherwitzl et al., Phys. Rev. Lett. 106 (2011) Son et al., Appl. Phys. Lett. 96 (2010) Ioffe-Regel limit: k F l = h/e 2 = 25kΩ/sq --> 1 R s R s Tuning Dimensionality: Thin LaNiO 3 LSAT DyScO 3 LaAlO 3 SrTiO 3

Materials 286KChris Freeze Scherwitzl et al., Appl. Phys. Lett. 95 (2009) Tuning T MI with gate bias Tuning Dimensionality: Thin LaNiO 3

Materials 286KChris Freeze M—I Transition In Rare-Earth Nickelates And The Impact Of Structural Distortions Summary: Multiple methods to tune across metal-insulator transition in LnNiO 3 Distorting Ni – O – Ni bond angle Rare earth cation radius Pressure Oxygen deficiency (Ni oxidation state) Dimensionality

Materials 286KChris Freeze Citation Text Title