Superconductivity and magnetism in the KxMoO2−δ

Abstract

Coexistence between superconductivity and magnetism is reported for the KxMoO2−δ samples. Photoemission experiments show that the presence of Mo3+ ions is responsible for the weak ferromagnetic ordering observed in the KxMoO2−δ samples. Magnetic ordering temperature and superconducting critical temperature (TC) ratio range from 7 to 18 in this compound. These are the highest ratios reported so far for a magnetic superconductor. TC decreases with increasing potassium composition (x). For the first time, TC near 10 K is reported in the K-Mo-O system.

A magnetic field tuned metal–insulator transition in unconventional metallic K‐doped MoO

“…Diffractograms of all samples reported in this work show only peaks of the MoO phase related to monoclinic structure. More details about sample preparation can be found in previous reports . Transport measurements were performed in a Physical Properties Measurement System (PPMS) from 1.8 to 300 K under applied magnetic fields up to 9 T.…”

“…Recent experiments show evidence for superconductivity at 12 K in oxygen‐deficient MoO (), and coexistence of superconductivity and magnetism in the K‐doped MoO . Furthermore, unconventional metallic behavior has been reported in this system .…”

Superconductivity and Physical Properties in the KxMoO2-δ

“…This chapter will report results about recent studies on the K x MoO 2-δ system, which has suggested that K doping in the MoO 2 matrix causes defects leading to a magnetic ordering temperature and superconducting critical temperature (T C ) ratio ranging from 7 to 18 in this compound [10]. These are the highest ratios reported so far for a magnetic superconductor.…”

“…The low superconducting volume fraction is probably due to the appearance of the ferromagnetic ordering at higher temperatures (T M = 70 K), which can be seen in the Figure 3 (b). The superconducting state appears below the ferromagnetic transition and the ratio between critical temperature is T M / T C ~7 [10].…”

Estrutura cristalina e propriedades físicas do condutor anômalo KxMoO2-δ

“…Neste contexto pode-se sugerir uma possível correlação entre o comportamento não convencional, observado nas curvas R(T) em temperaturas abaixo de ~70K com a existência de pares de Cooper sem ordem de longo alcance. Isto parece corroborar com a observação de supercondutividade no sistemaK x MoO 2-δALVES, et al, 2012).Curvas de magnetização em função da temperatura foram obtidas para a amostra deK 0,05 MoO 2- resfriada com campo aplicado de 10 e 200 Oe, (Field Cooled), ou a campo nulo, (Zero Field Cooled), e são mostradas na figura 4.34.Figura 4.34 -Curvas de magnetização nos regimes ZFC e FC em função da temperatura para o K 0,05 MoO 2- (amostra E) medidas em (a) 200 Oe e (b) em 10 Oe. No inserto a ampliação da curva FC exibe maior detalhe do ordenamento magnético.…”