Abstract
This work measures the resistance difference of Ni nanowire from self-heating by using steady-state joule heating and electrical-resistance thermometry. Finally, we obtain the thermal conductivity of Ni nanowire. The experiments divide into two parts of Ni nanowires in different domain wall density and in different magnetic field to investigate the relationship between temperature and thermal conductivity. First, we measure the thermal conductivity in different domain wall density at temperature between 60 and 300K. Results show that thermal conductivity in higher domain wall density is smaller than in lower one. The thermal conductivity of Ni nanowires is about 31% of bulk at 300K and Lorentz number is obviously less than theoretical value 2.44×10-8 WΩ/K2. Second, we measure the thermal conductivity fixed in different static magnetic field at temperature between 10 and 300K. Results show that magnon and part of phonon are suppressed heat conduction by field. The thermal conductivity in higher field is smaller and until the field higher than 510 Gauss thermal conductivity tends to constant. The thermal conductivity of Ni nanowires is about 30% of bulk at 300K and Lorentz number is obviously less than theoretical value 2.44×10-8 WΩ/K2. Results show Ni nanowires are not followed Wiedemann-Franz law. Keywords：Ni nanowires, thermal conductivity, domain wall, magnetic field, and Lorenz number