Pressure-dependent reversible increase in T(c) for the ferrimagnetic 2-D Mn(II)(TCNE)I(OH2) and 3-D Mn(II)(TCNE)(3/2)(I3)(1/2)·zTHF organic-based magnets

Abstract

The pressure dependence of the magnetic properties of ferrimagnetic Mn(II)(TCNE)I(OH2) up to 14.05 kbar and Mn(II)(TCNE)(3/2)(I3)(1/2)·zTHF up to 14.32 kbar were studied. For Mn(II)(TCNE)I(OH2), two distinct pressure regions separated at ∼1 kbar were evident in both the temperature and the field-dependent magnetic measurements. No increase of the magnetic properties was observed in the low-pressure region, while significant increases to the magnetic ordering temperature, T(c), bifurcation temperature, T(b), coercive field, H(cr), and remnant magnetization, M(r), were evident in the high-pressure region. The T(c), T(b), H(cr), M(r), and M(5 T) reversibly increased from ambient pressure values of 169 K, 169 K, 690 Oe, 620 emuOe/mol, and 13,800 emuOe/mol to 257 K, 261 K, 1460 Oe, 2300 emuOe/mol, and 17,100 emuOe/mol at 14.05 kbar, respectively. For Mn(II)(TCNE)(3/2)(I3)(1/2)·zTHF, the T(c) and T(b) were nearly coincident and increased linearly from 173 and 173 K, respectively, at ambient pressure to 273 and 272 K, respectively, at 14.32 kbar. Thus, the T(c) increased at an average rate of 6.25 and 7.18 K/kbar for Mn(II)(TCNE)I(OH2) and Mn(II)(TCNE)(3/2)(I3)(1/2)·zTHF, respectively. For Mn(TCNE)(1/2)(I3)(1/2)·zTHF remnant magnetization and saturation magnetization did not significantly change with applied pressure. The H(cr) exhibited a linear increase from ambient pressure to 5.00 kbar, reaching 860 Oe, but only achieving 880 Oe at 14.32 kbar.