Review on Developments and Progress in Nickelate‐Based Heterostructure Composites and Superconducting Thin Films

Abstract

In the past decade, the rapid development of modern heterointerface growth and characterization techniques has stimulated great effort to research and design the extraordinary physical properties of transition metal heterostructure composite materials. Here, new physics originates from the rearrangement of orbital, charge, spin, and lattice and the resulting rebalancing of their mutual interactions. In this paper, recent experimental and theoretical progress in the design, preparation, characterization, and physical property measurement of LaNiO 3 -based heterostructure composites and the infinite-layer Ni 1+ nickelate superconducting thin films on (001) SrTiO 3 substrate is reviewed, mainly by the methods of various X-ray spectroscopy measurements, scanning transmission electron microscopy, and magneto-transport measurements. In these materials, the electronic structure and orbital occupation around the Fermi level are modified, enabling nickelate-based composite materials to exhibit new states of matter and physical phenomena, which are absent in the bulk constituents. Their confined structures, superconductivity, orbital polarization, charge transfer, electronic structures, magnetic properties, and X-ray spectroscopic analysis, are therefore highlighted, aiming at understanding unconventional superconducting mechanisms and designing new high-T c superconducting low-dimensional materials for device applications.

Charge Distribution across Capped and Uncapped Infinite‐Layer Neodymium Nickelate Thin Films

“…[10] Since these Vo run along the stripes, they have the same periodicity as them, contributing to intensities at Q = (± 1 3 , 0, ± 1 3 ) r.l.u. and Q = (± 2 3 , 0, ± 2 3 ) r.l.u. in the reciprocal space.…”

“…The particular way in which nickelates are prepared, that is presence/absence of a capping layer, combined with the subtle control of the crystal structure modification during the reduction process, is pivotal to attaining the zero-resistance state. [2][3][4] Apart from superconductivity, recent studies have also revealed the existence of charge ordering phenomena and magnetic excitations in IL-nickelate thin films, [5][6][7][8] the amplitudes of which mostly depend upon the particular sample preparation, that is presence/absence of a SrTiO 3 (STO) capping-layer and doping level. In particular, charge order (CO) has been observed in uncapped-IL NdNiO 2 samples and it is not much pronounced in the capped ones, which on the contrary host dispersing magnetic excitation with a bandwidth of circa 200 meV.…”

Tunable 5d-t2g Mott State and Monoatomic Layer Two-Dimensional Electron Gas Realized in Spin–Orbit-Coupled SrIrO3 through Heterostructuring

“…Experimentally, techniques for artificial heterointerface growth and characterization are widely employed to manipulate the electronic and magnetic structures of bulk materials. , This is achieved by modifying the chemical environment and creating polar discontinuities at the heterointerface. In this study, we thoroughly investigated the electronic properties of the (SrIrO 3 ) m /(LaTiO 3 ) 1 [(SIO) m /(LTO) 1 ] superlattices (SLs).…”

Flux Growth of Trilayer La4Ni3O10 Single Crystals at Ambient Pressure

“…Understanding the interplay of lattice, charge, spin, and orbital degrees of freedom and their controlled physical properties such as superconductivity, colossal magnetoresistance, metal–insulator transition, and multiferroicity are the central challenges in the research of strongly correlated materials. − Rare earth nickelates have attracted intense attention due to their emergent physical properties including unconventional superconductivity in the infinite-layer square planar R 1– x A x NiO 2 (R = La, Pr, Nd, A = Sr; R = La, A = Ca) − and quintuple-layer Nd 6 Ni 5 O 12 at ambient pressure and ∼80 K superconductivity in La 3 Ni 2 O 7 at 14.0–43.5 GPa, − metal–insulator transition and multiferroicity in RNiO 3 (R = Pr–Lu), , charge/spin stripes in R 2– x Sr x NiO 4 (R = La–Nd) and La 4 Ni 3 O 8 , , metallic behavior in the trilayer square planar Pr 4 Ni 3 O 8 with a large orbital polarization that mimics superconducting cuprates, and metal-to-metal transition originated from intertwined charge and spin density waves in the trilayer nickelates R 4 Ni 3 O 10 (R = La, Pr, Nd) . However, certain fundamental issues surrounding the physics of nickelates remain elusive. − These include but are not limited to the origin of superconductivity in the square planar layered nickelates and the Ruddlesden–Popper La 3 Ni 2 O 7 , the crystal structure and magnetic ground state of RNiO 2 , the magnetic ground states in RNiO 3 , etc. ,− To address these fundamental questions, single crystals are the ideal material platforms.…”