  Strain applied to a condensed-matter system can be used to engineer its
excitation spectrum via artificial gauge fields, or it may tune the system
through transitions between different phases. Here we demonstrate that strain
tuning of the ground state of otherwise highly degenerate frustrated systems
can induce novel phases, both ordered and disordered. For the classical
Heisenberg antiferromagnet on the kagome lattice, we show that weak triaxial
strain reduces the degeneracies of the system, leading to a classical spin
liquid with non-coplanar configurations, while stronger strain drives the
system into a highly unconventional state which displays signatures of both
spin-glass behavior and magnetic long-range order. We provide experimentally
testable predictions for the magnetic structure factor, characterize the
ground-state degeneracies and the excitation spectrum, and analyze the
influence of sample shape and boundaries. Our work opens the way to strain
engineering of highly frustrated magnets.
