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Takashi Hirai

Publications and source records attributed to Takashi Hirai.

3 recordsLinked to original sources

Anomalous inverse proximity effect in unconventional-superconductor junctions

We investigate the effects of Andreev bound states due to the unconventional pairing on the inverse proximity effect of ferromagnet/superconductor junctions. Utilizing quasiclassical Eilenberger theory, we obtain the magnetization penetrating into the superconductor. We show that in a wide parameter range the direction of the induced magnetization is determined by two factors: whether Andreev bound states are present at the junction interface and the sign of the spin-mixing angle. In particular, when Andreev bound states appear at the interface, the direction of the induced magnetization is opposite to that without Andreev bound states. We also clarify the conditions under which the inverted induced magnetization appears. Applying this novel effect helps distinguishing the pairing symmetry of a superconductor.

cond-mat.supr-con↗

Remarkable suppression of Josephson current on d-wave superconductor junction

Josephson current in superconductor/insulator/superconductor junction is studied theoretically. It is well known that when the zero-energy resonance state exists both side of superconducting interface, the behaver of the temperature dependence of the critical Josephson current is striking enhancement at low temperature. On the other hand it is reported that if $d+is$-wave exists at the interface, Josephson current is suppressed at low temperature. In this paper, we discuss the existence of the imaginary part of the pair potential at the interface and remarkable suppresses of dc Josephson current on d-wave superconductor 110-junction.

cond-mat.supr-con↗

Theory of the Josephson effect in superconductor / one-dimensional electron gas / superconductor junction

We present a theory for the Josephson effect in an unconventional superconductor / one-dimensional electron gas / unconventional superconductor (s/o/s) junction, where the Josephson current is carried by components injected perpendicular to the interface. When superconductors on both sides have triplet symmetries, the Josephson current is enhanced at low temperature due to the zero-energy states formed near the interface. Measuring Josephson current in this s/o/s junction, we can identify parity of the superconductor.

cond-mat.supr-con↗