Anomalous electron transport in epitaxial NdNiO3 films

Abstract

The growth was monitored by in-situ RHEED (reflection high energy electron diffraction). Fig. S1(a) shows the time dependence of intensity of specular reflection (0,0), recorded during the growth of NdNiO 3 (NNO) film on NdGaO 3 (NGO) substrate and layer-by-layer growth has been confirmed by the sharp drops during ablation and gradual recovery within next few seconds to the same level of intensity after the deposition of each unit cell. Inset of Fig. S1(b) shows RHEED pattern for the NNO film, recorded after cooling to room temperature. The streak patterns of specular and off-specular: (0 1), (0-1) reflections (in pseudo cubic (p.c.) notation) confirm the desired two-dimensional surface morphology. X-ray diffraction: Success of epitaxial growth along [0 0 1] p.c. has been further confirmed by 2θ-ω scan in X-ray diffraction (Fig. S1(b)). Each diffraction pattern consists of a sharp substrate peak, a broad film peak (indicated by solid triangle in Fig. S1(b)) and thickness fringes, arises due to the finite thickness of film. Out-of plane lattice constant (c p.c. of NNO films are found to be 3.75Å (STO), 3.78Å (NGO), 3.83Å (SPGO), 3.84Å (SLAO) and 3.86Å (YAO) and these follow the expected tetragonal distortion relation for the cube on cube growth.

Epitaxial stabilization of ultra thin films of high entropy perovskite

“…After confirming the high structural and morphological quality, we have investigated the electrical transport of the films. As reported earlier 28,31,38 , 15 uc NNO thin film on NGO substrate undergoes first order MIT (upper panel of Fig. 3(a)).…”

Atomic-scale observation of spontaneous hole doping and concomitant lattice instabilities in strained nickelate films

“…Notably, whereas the bulk-LNO, -PNO, and -NNO metals feature n-type carriers as expected in the context of conducting e g 1 electrons [22][23][24][25], the films become p-type regardless of being subject to tensile or compressive strains [21,[26][27][28][29][30]. Though firstly proposed as an effect of self-hole doping by a strain-induced negative charge-transfer gap [26], it is now understood that the phenomenon arises from the large hole pockets at Fermi surface of the strained films [11,21,[31][32][33][34]. Despite this reconstructed fermiology [21,[31][32][33][34], the strained nickelates grown on GdTiO 3 were reported to harbor electrons as a result of interfacial charge doping into the nickelates by an elaborately designed chemical-potential difference between the films and GdTiO 3 (e.g.…”

“…In the NNO/STO, the approximate chemical-potential difference of ∼1.8 eV (that of LNO/STO [37]) that tends to render an electron doping into the STO [19] could, however, add on complexities unnoticed in the hole-doped NdNiO 2 endeavor [35,36] and be further at odds with the observed p-type transport of NNO/ and LNO/STO [21,26,27,29]. An atomistic insight into how the ubiquitous factors of interfacial charge doping [19,37] and epitaxial strains [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] would impact the pristine bulk properties of nickelates across the finite space of heterointerfaces is unambiguously timely.…”

“…With the above wisdom in bulks, current advances in the nickelates center on emergent properties in thin films [19][20][21], and the three RT paramagnetic metals of LNO (a = 5.4573, c = 13.1462 Å), PNO (a = 5.4193, b = 5.3801, c = 7.6263 Å), and NNO (a = 5.3891, b = 5.3816, c = 7.6101 Å) compose the model materials [3]. Notably, whereas the bulk-LNO, -PNO, and -NNO metals feature n-type carriers as expected in the context of conducting e g 1 electrons [22][23][24][25], the films become p-type regardless of being subject to tensile or compressive strains [21,[26][27][28][29][30]. Though firstly proposed as an effect of self-hole doping by a strain-induced negative charge-transfer gap [26], it is now understood that the phenomenon arises from the large hole pockets at Fermi surface of the strained films [11,21,[31][32][33][34].…”

Probing Electronic and Magnetic Transitions of Short Periodic Nickelate Superlattices Using Synchrotron X-rays

“…1(e)-(f)). The (0 ±1/2) reflections in RENiO3 series arise due to the in-plane doubling of the unit cell with either orthorhombic or monoclinic symmetry [51,52]. The absence of these half-order spots in 1ENO/2LNO SL ( Fig.…”