Magnetic Ordering in an Organic Polymer

Abstract

We describe preparation and magnetic properties of an organic π-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.

Room-temperature organic ferromagnetism in the crystalline poly(3-hexylthiophene): Phenyl-C61-butyric acid methyl ester blend film

“…A popular strategy is to generate high-spin radicals or charge transfer complexes by doping or charge transfer. For example, an organic π-conjugated polymer, synthesized with large net spin quantum numbers through designing cross link and alternating connectivity of radical molecules with unequal spin quantum numbers, can order ferromagnetically at very low temperatures, below 10 K [9]. After that, significant efforts from multiple groups have been devoted to increasing the Curie temperature of synthetic organic ferromagnets up to roomtemperature and beyond, which is important for practical applications [5,6,8,10].…”

Low-temperature magnetic behavior of the organic-based magnet Na[FeO6(C10H6N)3]

“…The sodium salt of 1-nitroso-2-naphthol iron complex, Na[FeO 6 (C 10 H 6 N) 3 ], was synthesized by the reaction of bisulfite derivative of 1-nitroso-2-naphthol and iron (II) sulfate at the presence of NaOH and Na 2 CO 3 according to a procedure described in Ref. 17.…”

“…In this paper, the studies of the magnetic properties of the complex of iron with 1-nitroso-2-naphthol C 10 H 7 NO 2 in the form of sodium salt Na[FeO 6 (C 10 H 6 N) 3 ] are presented. The investigations have been performed over a temperature range of 1.5-200 K, in external magnetic fields up to 90 kOe and over a frequency range of 95-2000 Hz.…”

“…An alternative approach to organic magnets may be based on π-conjugated polymers with large magnetic moment and magnetic order at low temperatures [3][4][5][6].…”

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The static and dynamic aspects of magnetic behavior of the complex of iron with 1-nitroso-2-naphthol Na [FeO 6 (C 10 H 6 N) 3 ] as a function of temperature, frequency and magnetic field have been analysed. The ac susceptibility ( ac ) and dc magnetization (M dc ) were measured over a temperature range of 1.5-200 K in external magnetic field up to 90 kOe and over a frequency range of 95-2000 Hz.

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