  Nano/micro-scale mechanical properties of multiferroic materials can be
controlled by the external magnetic or electric field due to the coupling
interaction. For the first time, a modularized multi-field nanoindentation
apparatus for carrying out testing on materials in external
magnetostatic/electrostatic field is constructed. Technical issues, such as the
application of magnetic/electric field and the processes to diminish the
interference between external fields and the other parts of the apparatus, are
addressed. Tests on calibration specimen indicate the feasibility of the
apparatus. The load-displacement curves of ferromagnetic, ferroelectric and
magnetoelectric materials in the presence/absence of external fields reveal the
small-scale magnetomechanical and electromechanical coupling, showing as the
Delta-E and Delta-H effects, i.e. the magnetic/electric field induced changes
in the apparent elastic modulus and indentation hardness.
