Superconductivity in Te-Deficient ZrTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity Research

Background:

• Zirconium ditelluride (ZrTe2) is a nonsuperconducting material with a specific crystal structure.
• Understanding the factors influencing superconductivity in related materials is crucial for discovering new superconductors.

Purpose of the Study:

• To investigate the superconducting properties of Te-deficient ZrTe1.8 single crystals.
• To elucidate the role of Te deficiency in modifying the electronic structure and promoting superconductivity.

Main Methods:

• Growth of high-quality ZrTe1.8 single crystals using isothermal chemical vapor transport.
• Measurements of structural, electrical, and thermoelectric properties.
• Analysis of superconducting critical field using a two-gap superconducting model.
• First-principles density functional theory (DFT) calculations.

Main Results:

• ZrTe1.8 exhibits superconductivity below 3.2 K.
• The upper critical field behavior deviates from single-band models, fitting a two-gap model.
• Seebeck potential measurements indicate predominantly negative charge carriers.
• DFT calculations reveal density of states peaks at the Fermi level due to localized Zr-d bands caused by Te deficiency.

Conclusions:

• Te deficiency in ZrTe1.8 unexpectedly creates electronic instabilities at the Fermi level, enhancing superconductivity.
• Defects can be strategically used to tune electronic structures for superconductivity.
• ZrTe1.8 presents a promising system for exploring defect-engineered superconductors.