  LiFePO$_4$ (LFPO) is an archetypical and well-known cathode material for
rechargeable Li-ion batteries. However, its quasi-one-dimensional (Q1D)
structure along with the Fe ions, LFPO also displays interesting
low-temperature magnetic properties. Our team has previously utilized the muon
spin rotation ($\mu^+$SR) technique to investigate both magnetic spin order as
well as Li-ion diffusion in LFPO. In this initial study we extend our
investigation and make use of high-pressure $\mu^+$SR to investigate effects on
the low-$T$ magnetic order. Contrary to theoretical predictions we find that
the magnetic ordering temperature as well as the ordered magnetic moment
increase at high pressure (compressive strain).

Strongly Correlated Electrons