Percolative Superconductivity in Mg1−xB2

P. A. Sharma; N. Hur; Y. Horibe; C. H. Chen; B. G. Kim; S. Guha; Marta Z. Cieplak; S-W. Cheong

doi:10.1103/PhysRevLett.89.167003

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Percolative Superconductivity in Mg1−xB2

P. A. Sharma, N. Hur, Y. Horibe, C. H. Chen, B. G. Kim, S. Guha, Marta Z. Cieplak, S-W. Cheong

DOI 10.1103/PhysRevLett.89.167003 · Physical Review Letters

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Abstract

Our results from various transport experiments on Mg1−xB2 indicate a surprising effect associated with the presence of a Mg deficiency in MgB2: the phase separation between Mg-vacancy rich and Mg-vacancy poor phases. The Mg-vacancy poor phase is superconducting, but the insulating nature of the Mg-vacancy rich phase probably originates from the Anderson (disorder-induced) localization of itinerant carriers. Furthermore, electron diffraction measurements indicate that within vacancy-rich regions these defects tend to order with intriguing patterns. This electronic phase separation in Mg1−xB2 shows similar, but also distinct characteristics compared with that observed in La2CuO4+δ.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	35	Pressure not reported	onset
Mg1-xB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	onset
La2CuO4+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown