Microstructure and magnetic disorder induced by nanoindentation in single-crystalline Fe

Using molecular dynamics simulation, we study nanoindentation into an Fe (100) surface. We use the so-called magnetic interaction potentials provided by Dudarev and Derlet [J. Phys.: Condens. Matter 17, 7097 (2005)] and Chiesa et al. [ibid. 23, 206001 (2011)] in three different parametrizations; these allow us to extract information about the local magnetic moments from the molecular-dynamics simulation. Our simulations are performed at low temperature; the simulation cell is assumed to consist of a single ferromagnetic domain. Material hardness as well as the density of dislocations generated coincide satisfactorily with previous studies using conventional potentials. We observe the generation of both b = 1/2 < 111 > and b = < 100 > dislocations, which contribute to the plastic deformation. Besides dislocations, the induced microstructure features twins and vacancies. The local magnetic moments change considerably due to the strain field induced by the developing microstructure and assume values between 83 and 112% of the equilibrium bulk value in Fe. These changes are, however, quite localized and quickly decay away from the highly strained regions of dislocation cores.