Undoped cuprates have long been considered to be antiferromagnetic insulators. In this article, however, we report that superconductivity is achieved in undoped T'-RE2CuO4 (RE = Pr, Nd, Sm, Eu, and Gd). Our discovery was performed by using metal-organic decomposition (MOD), an inexpensive and easy-to-implement thin-film process. The keys to prepare the superconducting films are firing with low partial-pressure of oxygen and reduction at low temperatures. The highest Tc of undoped T'-RE2CuO4 is over 30 K, substantially higher than "electron-doped" analogs. Remarkably, Gd2CuO4, even the derivatives of which have not shown superconductivity so far, gets superconducting with Tconset as high as ~ 20 K. The implication of our discovery is briefly discussed.
@article{arxiv.0805.4463,
title = {Superconductivity in undoped T' cuprates with Tc over 30 K},
author = {Osamu Matsumoto and Aya Utsuki and Akio Tsukada and Hideki Yamamoto and Takaaki Manabe and Michio Naito},
journal= {arXiv preprint arXiv:0805.4463},
year = {2013}
}
Comments
22 pages, 5 figures, submitted to Physical Review Letters