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Interface-induced superconductivity and strain-dependent spin density waves in FeSe/SrTiO3 thin films
Shiyong Tan1, Yan Zhang, Miao Xia
1State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
Nature Materials
|May 28, 2013
Summary
Researchers found that spin density waves (SDWs) in iron-based high-temperature superconductors (Fe-HTS) weaken with thickness or strain. Suppressing SDWs in single-layer FeSe films enhances superconductivity, potentially reaching 65 K.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- The record superconducting transition temperature (T(c)) for iron-based high-temperature superconductors (Fe-HTS) has been 56 K.
- Recent studies indicated a potential new record of 65 K in single-layer iron selenide (FeSe) films on strontium titanate (SrTiO3) substrates.
Purpose of the Study:
- To substantiate the presence and role of spin density waves (SDWs) in FeSe films.
- To understand the mechanism behind the enhanced superconductivity in single-layer FeSe.
- To map the phase diagram of FeSe and its relation to Fe-HTS physics.
Main Methods:
- In situ photoemission spectroscopy measurements.
- Growth of single-layer FeSe films on SrTiO3 substrates.
- Tuning film thickness and substrate strain.
Main Results:
- Confirmed the presence of spin density waves (SDWs) in FeSe films, a previously overlooked factor in Fe-HTS.
- Observed that SDWs weaken with increased film thickness or reduced substrate strain.
- Demonstrated that superconductivity is enhanced when substrate-induced electron transfer suppresses SDWs in single-layer FeSe.
Conclusions:
- Single-layer FeSe films provide a simplified model system for understanding Fe-HTS.
- Suppression of SDWs is crucial for achieving higher superconducting transition temperatures (T(c)).
- The phase diagram of FeSe offers insights into the essential physics governing all Fe-HTS.
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