FeSe
(For Te-substituted Fe(Te,Se), see this page 🔗.)
Structure
Crystal Image
Crystal Structure
The real samples usually have excess Fe at the interstitial sites of the Te/Se layer, forming Fe1+ySe composition. Such excess affects the electronic transport (superconducting) properties.
Structural property summary
- Single crystal form: silver color, metallic luster, square/rectangle facets
- Structure type: Layered, P4/nmm
- Air sensitivity: gradually degrade in a year
- Exfoliation: very easy
Transport Properties
Resistivity- Temperature dependence
- The transition temperature is affected by sample quality and amount of excess Fe.
- For samples with less excess Fe, there is structure transition around 90K and Tc ~ 8-12K
- Te substitution for Se increases Tc to 15K at the optimal doping (Te/Se = 0.4/0.6 to 0.5/0.5). See Fe(Te,Se) in the database
Resistivity- Temperature dependence under different field
FeSe has a very high upper critical field (~ 30T) for H//c
Magnetic Properties
Magnetization- Temperature dependence
Meissner effect
Superconducting hysteresis loop
Specific Heat
Specific Heat (C/T vs T)