Chapter Eight:Competing interactions and low dimensionality 1.Teaching aims Know some of the ways in which competing interactions and low dimensionality can lead to some extremely subtle,complex,and sometimes even useful magnetic behaviour in solids. 2. Keypoints and Difficulties Keypoints:Spin glasses:Superparamagnetism Difficulties:Spin glasses 3.Contents 8.1 Frustration 8.2 Spin glasses 8.3 Superparamagnetism 8.4 One-dimensional magnets 8.4.1 Spin chains 8.4.2 Spinons 8.4.3 Haldane chains 8.4.4 Spin-Peierls transition 8.4.5 Spin ladders 8.5 Two-dimensional magnets 8.6 Quantum phase transitions 8.7 Thin films and multilayers 8.8 Magneto-optics 8.9 Magnetoresistance 8.9.1 Magnetoresistance of ferromagnets 8.9.2 Anisotropic magnetoresistance 8.9.3 Giant magnetoresistance 8.9.4 Exchange anisotropy 8.9.5 Colossal magnetoresistance 8.9.6 Hall effect 8.10 Organic and molecular magnets Chapter Eight: Competing interactions and low dimensionality 1. Teaching aims Know some of the ways in which competing interactions and low dimensionality can lead to some extremely subtle, complex, and sometimes even useful magnetic behaviour in solids. 2. Keypoints and Difficulties Keypoints: Spin glasses; Superparamagnetism Difficulties: Spin glasses 3. Contents 8.1 Frustration 8.2 Spin glasses 8.3 Superparamagnetism 8.4 One-dimensional magnets 8.4.1 Spin chains 8.4.2 Spinons 8.4.3 Haldane chains 8.4.4 Spin-Peierls transition 8.4.5 Spin ladders 8.5 Two-dimensional magnets 8.6 Quantum phase transitions 8.7 Thin films and multilayers 8.8 Magneto-optics 8.9 Magnetoresistance 8.9.1 Magnetoresistance of ferromagnets 8.9.2 Anisotropic magnetoresistance 8.9.3 Giant magnetoresistance 8.9.4 Exchange anisotropy 8.9.5 Colossal magnetoresistance 8.9.6 Hall effect 8.10 Organic and molecular magnets