Cylindrical ising nanowire and nanotube with a negative exchange interaction at the surface: Remarkable surface effects

• Phase diagrams and magnetizations are discussed for nanowire and nanotube.
• The effects of interlayer and negative couplings at the surface on them are examined.
• Some phenomena due to the frustrated spin configuration at the surface are reported.
• These properties are examined by the use of the EFT.

The phase diagrams and temperature dependences of magnetizations in cylindrical Ising nanowire and nanotube are studied by the uses of the effective-field theory with correlations (EFT) and the core–shell concept, where a negative exchange interaction is selected at the surface shell and two positive exchange interactions are taken in the core and between the core and the surface shell. Some unconventional features, such as the possibility of re-entrant phenomena being free from disorder induced frustration, are obtained for the magnetic properties in such systems.