Mingxiang Xu, Yoshihiko Takano, Takeshi Hatano, Masayo Kitahara, Daisuke Fujita

National Institute for Materials Science,

Tsukuba, Japan

LT 23, Hiroshima, JAPAN

E-mail: XU.Mingxiang@nims.go.jp

ABSTRACTABSTRACT

Reproducible, clean and stable MgB2 superconducting tips have been fabricated.

The quality of these tips has been verified by imaging the surface of a thin Au(111) film using a low temperature STM.

High-quality semi-atomically resolved STM images of the thin Au(111) film sample have been observed.

BACKGROUND & MOTIVATIONSBACKGROUND & MOTIVATIONS

Conventional STM studies for superconducting materials: superconductor/insulator/normal-metal (S/I/N) configuration.

Quasiparticle tunneling using a superconducting atomically sharp Nb tip: S/I/S measurements, OK!

MgB2: Suitable for use as STM tips? Feasible?

Josephson tunneling in SS-STM: Tunable Josephson junction !!

Fig. 1. (a) Optical image of the MgB2 tip. (b) Enlarged image.

Fig. 2. Schematic depiction

of the experimental setup

Fig. 3.

Fig. 3. A wide-area STM image (104 × 104 nm2) at the constant-height mode (VT = -2.00 V, IT = 0.20 nA) of the reconstructed Au(111) surface observed at 30 K,clearly showing the steps of monoatomic height and the herringbone patterns.

FFurther STM studiesby the MgB2 tip

MgB2 superconducting tip + MgB2 sample.

MgB2 two gaps nature.

SS-STM: Tunable Josephson junction.

Fig. 4. Schematic depiction

for further experiments

CONCLUSIONCONCLUSION

Reproducible, clean and stable MgB2 superconducting tips have been fabricated.

MgB2: Suitable for use as STM tips, is feasible!

Application: Josephson tunneling in SS-STM: Tunable Josephson junction !!