Pressure-induced superconductivity in SnSb2Te4

At a Glance

Metadata	Details
Publication Date	2020-02-17
Journal	Journal of Physics Condensed Matter
Authors	Peng Song, Ryo Matsumoto, Zhufeng Hou, Shintaro Adachi, Hiroshi Hara
Institutions	National Institute for Materials Science, Fujian Institute of Research on the Structure of Matter
Citations	12
Analysis	Full AI Review Included

Executive Summary

This study reports the discovery and characterization of pressure-induced superconductivity in the phase change material (PCM) SnSb₂Te₄, providing a new avenue for exploring superconducting properties in chalcogenide compounds.

New Superconductor: SnSb₂Te₄, typically a narrow-gap semiconductor (~0.26 eV), exhibits superconductivity when subjected to high pressure.
Pressure-Induced Transition: Applied pressure causes a transition to metallic behavior, with the Fermi level crossing the valence bands at 10 GPa.
Critical Temperature (T_c): Superconductivity onset (T_c^onset) was first detected at 2.1 K under 8.1 GPa.
Maximum Performance: The maximum T_c^onset achieved was 7.4 K under the highest measured pressure of 32.6 GPa.
Mechanism Insight: First-principles calculations suggest that pressure shrinks the Sn-Te and Sb-Te bond lengths, shifting anti-bonding states toward higher energy, which decreases the band gap and facilitates electron-phonon coupling (BCS mechanism).
Material Potential: The high calculated Debye temperature (Θ_R ≈ 320 K) supports the material’s potential for superconductivity under favorable conditions.

Technical Specifications

Parameter	Value	Unit	Context
Maximum Superconducting T_c (onset)	7.4	K	Measured at 32.6 GPa
Minimum Pressure for T_c (onset)	8.1	GPa	T_c = 2.1 K
Pressure for Zero Resistivity (T_c^zero)	10.2	GPa	T_c^zero ≈ 2.2 K
Maximum Pressure Measured	32.6	GPa	Resistance dependence study
Ambient Band Gap (Calculated)	~0.26	eV	GGA-PBE calculation at Z point
Ambient Crystal Structure	Trigonal (R-3m)	N/A	Layered structure
Ambient Lattice Constant (a=b)	4.304(1)	A	Powder XRD data
Ambient Lattice Constant (c)	41.739(3)	A	Powder XRD data
Calculated Debye Temperature (Θ_R)	~320	K	Derived from Bloch-Gruneissen resistivity fitting (6K to 200K)
Stoichiometric Composition (EDS)	Sn_1.01Sb_1.98Te₄	N/A	Good agreement with nominal composition

Key Methodologies

Material Synthesis (Conventional Melting-Growth Method)

Precursor Preparation: Sn (99.9% powder), Sb (99.99% powder), and Te (99.9% grain) were combined in stoichiometric ratios (SnSb₂Te₄).
Encapsulation: The mixture was sealed in an evacuated silica tube.
Heating: Heated in a furnace up to 1010 K for 10 hours.
Cooling: Slowly cooled to 873 K at a rate of 9.1 K h^-1 and held at that temperature for 24 hours to grow single crystals.

Experimental Measurements

Pressure Application: Resistance measurements under pressure were conducted using an originally designed Diamond Anvil Cell (DAC).
Electrodes: Boron-doped diamond electrodes were used for electrical measurements.
Structural Analysis: Room temperature Powder X-ray Diffraction (XRD) was performed using a Mini Flex 600 (Rigaku).
Compositional Analysis: Energy Dispersive Spectroscopy (EDS) was used to confirm the material composition.
Resistivity Fitting: Temperature-dependent resistivity (4.5 K to 296 K) was fitted using the Bloch-Gruneissen formula to determine the Debye temperature (Θ_R).

Computational Methods (First-Principles Calculations)

Software: Quantum ESPRESSO software package (Projector Augmented Wave, PAW method).
Functional: Generalized Gradient Approximation (GGA) of Perdew-Burke-Erzerhof (PBE) for exchange-correlation.
Bonding Analysis: Crystal Orbital Hamilton Population (COHP) and its energy integral (ICOHP) were calculated using LOBSTER to analyze bonding states.
Relaxation: Atomic positions and lattice parameters were relaxed using the Broyden-Fletcher-Goldfard-Shanno (BFGS) algorithm.

Commercial Applications

The research on SnSb₂Te₄, a phase change material exhibiting pressure-induced superconductivity, has implications across several advanced technology sectors:

Phase Change Memory (PCM): As a member of the Ge-Sb-Te family of PCMs, SnSb₂Te₄ is fundamentally relevant to high-density, nonvolatile data storage and rewriteable media.
Pressure-Tunable Quantum Devices: The ability to induce a superconducting state (T_c up to 7.4 K) via pressure suggests potential for developing active quantum devices where electronic properties can be dynamically tuned by mechanical stress.
Topological Electronics: Given that related compounds (like Sb₂Te₃) are topological insulators, the pressure-induced superconductivity in SnSb₂Te₄ may be topologically non-trivial, relevant for fault-tolerant quantum computing and spintronics.
Thermoelectric Energy Conversion: The layered structure and narrow band gap at ambient pressure are favorable characteristics for high-performance thermoelectric materials, allowing for efficient conversion between heat and electrical energy.
Advanced Sensor Technology: Materials that undergo sharp metal-insulator or metal-superconductor transitions under specific pressure ranges can be utilized in highly sensitive, miniaturized pressure transducers and gauges.

View Original Abstract

Here we firstly report the pressure-induced superconductivity in phase change materials SnSb2Te4. Single crystals of SnSb2Te4 were grown using a conventional melting-down method. The resistance under pressure was measured using an originally designed diamond anvil cell with boron-doped diamond electrodes. The temperature dependence of the resistance under different pressures has been measured up to 32.6 GPa. The superconducting transition of SnSb2Te4 appeared at 2.1 K ([Formula: see text]) under 8.1 GPa, which was further increased with applied pressure to a maximum onset transition temperature 7.4 K under 32.6 GPa.

Tech Support

Original Source

DOI: https://doi.org/10.1088/1361-648x/ab76e2