Magnetic Characterization of Direct-Write Free-Form Building Blocks for Artificial Magnetic 3D Lattices

Three-dimensional (3D) nanomagnetism, where spin configurations extend into the verticaldirection of a substrate plane allow for more complex, hierarchical systems and the design of novelmagnetic effects. As an important step towards this goal, we have recently demonstrated thedirect-write fabrication of freestanding ferromagnetic 3D nano-architectures of ferromagnetic CoFe inshapes of nano-tree and nano-cube structures by means of focused electron beam induced deposition.Here, we present a comprehensive characterization of the magnetic properties of these structures bylocal stray-field measurements using a high-resolution micro-Hall magnetometer. Measurementsin a wide range of temperatures and different angles of the externally applied magnetic field withrespect to the surface plane of the sensor are supported by corresponding micromagnetic simulations,which explain the overall switching behavior of in part rather complex magnetization configurationsremarkably well. In particular, the simulations yield coercive and switching fields that are in goodquantitative correspondence with the measured coercive and switching fields assuming a bulk metalcontent of 100 at% consisting of bcc Co3Fe. We show that thermally-unstable magnetization states canbe repetitively prepared and their lifetime controlled at will, a prerequisite to realizing dynamic andthermally-active magnetic configurations if the building blocks are to be used in lattice structures.