Large Coercivity and High Remanent Magnetization Organic-based Magnets, D. K. Rittenberg, K-i. Sugiura, Y. Sakata, S. Mikami, A. J. Epstein, J. S. Miller, Adv. Mater. 12, 126-130 (2000).

Abstract

Anomalous high coercive field, Hcr, magnets exhibiting large remanence magnetizations have been prepared from electron transfer salts of tetracyanoethylene and MnII(porphyrin), as typified by [MnIIITBrPP]+[TCNE]•- (TBrPP = meso-tetrakis(4-bromophenyl)porphinato). These magnets exhibit metamagnetic-like behavior at low temperature, but anomalously exhibit hysteresis with a large remanent magnetization. This example has a large metamagnetic-like critical field of 27.8 kOe, as well as a very large Hcr of 27.0 kOe (2.16 MA/m) at 2 K. Metamagnets exhibiting coercivity and remanence magnetizations, especially large values, represent a phenomenon that may lead to the discovery of new technologically important materials.

M(H) for [MnIIITBrPP]+[TCNE].-. at 2.0 (o), 3.0 (o), 4.0 (G), 4.8 (D), 5.2 (x), 5.5 (-), 6.1 (|), and 6.8 (.) K showing the high coercivity at low temperature.

~Larger Coercive Fields (Hcr) at Lower Temperature

T < 6 K Þ Hcr > 0 27,000 Oe (2 K) T > 6 K Þ Hcr = 0

þ

Metamagnetic-like Behavior

Large Critical Field (Hc): 27,800 Oe @ 2 K

~Large Remanent Magnetization (Mr)

11,500 emuOe/mol @ 2 K

~Saturation Does Not Occur (<Ms) ( H < 120,000 Oe)

Very Complex Magnetic Behavior

Tc (Metamagnetic-like Ordering T) = 5.3 ± 0.1 K