Origin of the 2D Electron Gas at the SrTiO Surface.

Bulk SrTiO is a well-known band insulator and the most common substrate used in the field of complex oxide heterostructures. Its surface and interface with other oxides, however, have demonstrated a variety of remarkable behaviors distinct from those expected. In this work, using a suite of in situ techniques to monitor both the atomic and electronic structures of the SrTiO (001) surface prior to and during growth, the disappearance and re-appearance of a 2D electron gas (2DEG) is observed after the completion of each SrO and TiO monolayer, respectively.

Self-healing Growth of LaNiO on a Mixed-Terminated Perovskite Surface.

Developing atomic-scale synthesis control is a prerequisite for understanding and engineering the exotic physics inherent to transition-metal oxide heterostructures. Thus, far, however, the number of materials systems explored has been extremely limited, particularly with regard to the crystalline substrate, which is routinely SrTiO. Here, we investigate the growth of a rare-earth nickelate─LaNiO─on (LaAlO)(SrAlTaO) (LSAT) (001) by oxide molecular beam epitaxy (MBE).

Observation of an antiferromagnetic quantum critical point in high-purity LaNiO.

Amongst the rare-earth perovskite nickelates, LaNiO (LNO) is an exception. While the former have insulating and antiferromagnetic ground states, LNO remains metallic and non-magnetic down to the lowest temperatures. It is believed that LNO is a strange metal, on the verge of an antiferromagnetic instability.

High-Temperature Thermoelectricity in LaNiO-LaCuO Heterostructures.

Transition metal oxides exhibit a high potential for application in the field of electronic devices, energy storage, and energy conversion. The ability of building these types of materials by atomic layer-by-layer techniques provides a possibility to design novel systems with favored functionalities. In this study, by means of the atomic layer-by-layer oxide molecular beam epitaxy technique, we designed oxide heterostructures consisting of tetragonal KNiF-type insulating LaCuO (LCO) and perovskite-type conductive metallic LaNiO (LNO) layers with different thicknesses to assess the heterostructure-thermoelectric property-relationship at high temperatures.

Partial spin ordering and complex magnetic structure in BaYFeO4: a neutron diffraction and high temperature susceptibility study.

The novel iron-based compound, BaYFeO4, crystallizes in the Pnma space group with two distinct Fe(3+) sites, that are alternately corner-shared [FeO5](7-) square pyramids and [FeO6](9-) octahedra, forming into [Fe4O18](24-) rings, which propagate as columns along the b-axis. A recent report shows two discernible antiferromagnetic (AFM) transitions at 36 and 48 K in the susceptibility, yet heat capacity measurements reveal no magnetic phase transitions at these temperatures. An upturn in the magnetic susceptibility measurements up to 400 K suggests the presence of short-range magnetic behavior at higher temperatures.

Antiferromagnetic spin correlations between corner-shared [FeO5]7- and [FeO6]9- units, in the novel iron-based compound: BaYFeO4.

A novel quaternary compound in the Ba-Y-Fe-O phase diagram was synthesized by solid-state reaction and its crystal structure was characterized using powder X-ray diffraction. The crystal structure of BaYFeO4 consists of a unique arrangement of Fe(3+) magnetic ions, which is based on alternate corner-shared units of [FeO5](7-) square pyramids and [FeO6](9-) octahedra. This results in the formation of stairwise channels of FeO polyhedra along the b crystallographic axis.