Thickness controlled proximity effects in C-type antiferromagnet/superconductor heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism and Superconductivity

Background:

• Superconducting heterostructures offer a platform to study the interplay between magnetism and superconductivity.
• The Nd0.35Sr0.65MnO3/YBa2Cu3O7 system exhibits a C-type antiferromagnetic phase with potential to modulate superconductivity.

Purpose of the Study:

• To investigate the modulation of the superconducting state in Nd0.35Sr0.65MnO3/YBa2Cu3O7 heterostructures by varying the thickness of the Nd0.35Sr0.65MnO3 layer.
• To understand the influence of antiferromagnetism and spin canting on superconducting properties.

Main Methods:

• Fabrication of Nd0.35Sr0.65MnO3/YBa2Cu3O7 heterostructures with varying Nd0.35Sr0.65MnO3 layer thicknesses (40-200 nm).
• Characterization of superconducting properties, including transition temperature, critical field, coherence length, and critical current density.
• Investigation of low-temperature spin canting effects and magnetoresistance.

Main Results:

• Superconducting transition temperature and upper critical field decrease with increasing Nd0.35Sr0.65MnO3 thickness.
• In-plane coherence length increases, and critical current density shows field-independent behavior, indicating enhanced flux pinning.
• Spin canting induces superconductivity breakdown and re-entrance, alongside an unexpected colossal magnetoresistance at thicker layers.

Conclusions:

• The interplay between superconducting pairing and exchange fields dictates the observed superconducting behavior.
• Enhanced flux pinning is achieved with increasing magnetic layer thickness.
• The exchange field's dominance over pairing energy can lead to colossal magnetoresistance in these heterostructures.