This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Hofstadter's butterfly. Hofstadter's butterfly in color The horizontal axis is the energy or chemical potential and the vertical axis is the magnetic flux through the unit cell The warm and cold colors represent positive and negative values of Hall conductance respectively The butterfly was discovered by Douglas Hofstadter in his