  A2Ir2O7 iridates were proven to crystallise in the geometrically frustrated
pyrochlore structure, which remains stable upon rare-earth cation substitution,
temperature variation, and external pressure application. However, the change
of interatomic distances and local distortions in the lattice frequently leads
to complex electronic properties. The low-temperature behaviour in light-A
iridates has been thoroughly investigated, including its evolution with
pressure. The present pressure study reports the electrical transport and
magnetotransport properties in heavy rare-earth Lu2Ir2O7 and Er2Ir2O7. Both
compounds reveal a semiconductor-to-insulator transition induced by the
antiferromagnetic ordering of the all-in-all-out (AIAO) type in the Ir
sublattice. The transition monotonously shifts to a higher temperature under
applied pressure by approximately 20 K at 3 GPa. As the transition in
resistivity originates in the antiferromagnetic order, the latter is expected
to be enhanced with the applied pressure as well. Upon cooling the compound in
a magnetic field, the AIAO/AOAI domain structure with non-zero net magnetic
moment is formed, mirroring itself in an asymmetric term in the
magnetoresistance of Lu2Ir2O7. The application of pressure then enhances the
asymmetric term. The same behaviour is proposed for the whole heavy rare-earth
A2Ir2O7 series (A = Gd - Lu), although with magnetoresistance features masked
significantly by a stronger response of magnetic A cations.
