Magnetic Ordering in an Organic Polymer

Andrzej Rajca, University of Nebraska - Lincoln
Jirawat Wongsriratanakul
Suchada Rajca, University of Nebraska-Lincoln

Document Type Article

Published in SCIENCE VOL 294 16 NOVEMBER 2001. Copyright 2001. Used by permission. www.sciencemag.org

Abstract

We describe preparation and magnetic properties of an organic p-conjugated polymer with very large magnetic moment and magnetic order at low temperatures. The polymer is designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S = 2 and, cross-linking S = ½ modules, which permits large net S values for either ferromagnetic or antiferromagnetic exchange couplings between the modules. In the highly cross-linked polymer, an effective magnetic moment corresponding to an average S of about 5000 and slow reorientation of the magnetization by a small magnetic field (less than or equal to 1 oersted) below a temperature of about 10 kelvin are found. Qualitatively, this magnetic behavior is comparable to that of insulating spin glasses and blocked superparamagnets.