Unconventional metallic behavior and superconductivity in the K-Mo-O system

Abstract

Transport properties and magnetization measurements of the K x MoO 2−␦ ͑0 Յ x Յ 0.25͒ compound are reported. The compound crystallizes in the oxygen deficient MoO 2 monoclinic structure with potassium atoms occupying interstitial positions. An unconventional metallic behavior with power-law temperature dependence is related to a magnetic ordering. Superconducting transition with small volume fraction is also observed near 7 K for a sample with low potassium composition.

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

“…At zero field, an anomaly can be noticed below 70 K in which reduces at low temperatures instead of showing a typical saturation or linear T dependence such as for conventional metal like behavior. As reported before, this unconventional metallic behavior is typical for the KMoO system (). Near K, the sample also displays a phase transition.…”

“…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 . The nature of this unconventional metallic behavior remains unclear.…”

Microstructure and metal-insulator transition in single crystalline KMo4O6

“…Remanent magnetization and coercive field are weak temperature dependent. On the other hand, the hysteresis curves at low field follow the same trend for the curves measured at high magnetic fields above and below 80 K. The origin of the magnetic ordering in the KMo 4 O 6 is still under investigation but results performed in other molybdate compounds 8,17 suggest that the presence of Mo ions with different valences could be responsible for the weak ferromagnetic moment observed in Figure 6.…”

“…Furthermore, it shows a crossover from metal to insulator at low temperatures and becomes an anisotropic superconductor below 1.9 K 7 . Recently, our group has found anisotropic properties in a new phase with stoichiometry K x MoO 2-δ [8] . This compound has an anomalous metallic behavior at low temperatures which is related to a weak magnetic ordering.…”