We investigated the magnetic phase of the perovskite CaCrO3 by using the
muon spin relaxation technique accompanied by susceptibility measurements. A
thermal hysteresis loop is identified with a width of about 1 K at the
transition temperature. Within the time scale of the muon lifetime, a static
antiferromagnetic order is revealed with distinct multiple internal fields
which are experienced in the muon interstitial sites below the phase-transition
temperature, TN=90K. Above TN, lattice deformations are indicated by
transverse-field muon-spin rotation and relaxation suggesting a magneto-elastic
mechanism.Comment: 5 pages, 4 figures. Accepted for publication in PR