Arguello Cruz Erick, Ducos Pedro, Gao Zhaoli, Johnson Alan T Charlie, Niebieskikwiat Dario
Departamento de Fisica, Colegio de Ciencias e Ingenierias, Universidad San Francisco de Quito, Quito 170901, Ecuador.
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.
Nanomaterials (Basel). 2023 Jun 15;13(12):1861. doi: 10.3390/nano13121861.
We characterize the effect of ferromagnetic nickel nanoparticles (size ∼6 nm) on the magnetotransport properties of chemical-vapor-deposited (CVD) graphene. The nanoparticles were formed by thermal annealing of a thin Ni film evaporated on top of a graphene ribbon. The magnetoresistance was measured while sweeping the magnetic field at different temperatures, and compared against measurements performed on pristine graphene. Our results show that, in the presence of Ni nanoparticles, the usually observed zero-field peak of resistivity produced by weak localization is widely suppressed (by a factor of ∼3), most likely due to the reduction of the dephasing time as a consequence of the increase in magnetic scattering. On the other hand, the high-field magnetoresistance is amplified by the contribution of a large effective interaction field. The results are discussed in terms of a local exchange coupling, J∼6 meV, between the graphene π electrons and the magnetic moment of nickel. Interestingly, this magnetic coupling does not affect the intrinsic transport parameters of graphene, such as the mobility and transport scattering rate, which remain the same with and without Ni nanoparticles, indicating that the changes in the magnetotransport properties have a purely magnetic origin.
我们研究了铁磁性镍纳米颗粒（尺寸约6纳米）对化学气相沉积（CVD）石墨烯磁输运性质的影响。这些纳米颗粒是通过对蒸发在石墨烯带顶部的薄镍膜进行热退火形成的。在不同温度下扫描磁场时测量磁电阻，并与在原始石墨烯上进行的测量结果进行比较。我们的结果表明，在存在镍纳米颗粒的情况下，通常由弱局域化产生的零场电阻率峰值被广泛抑制（约为3倍），这很可能是由于磁散射增加导致退相时间缩短所致。另一方面，高场磁电阻因大有效相互作用场的贡献而增大。结果从石墨烯π电子与镍磁矩之间约6毫电子伏特的局部交换耦合J的角度进行了讨论。有趣的是，这种磁耦合并不影响石墨烯的本征输运参数，如迁移率和输运散射率，有无镍纳米颗粒时这些参数保持不变，这表明磁输运性质的变化具有纯粹的磁起源。
