Hysteresis Applet

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Fit: To zoom in so that the loop completely fills the display, press this button. Zoom Out: To zoom out in the view of the hysteresis loop, press this button.
Generate Loop: To generate an entire hysteresis loop, press this button. STOP: To stop the simulation, press this button.
Configure: To configure the details of the simulation, press this button. Disorder: To change the disorder, type a new value here.
Changing the field: Click a point in the loop view to change the field to the value at that point.
Zooming To zoom in on the hysteresis loop, drag a box around the area you want to view. To zoom out, press the Zoom Out button. To zoom so that the loop fills the display, press the Fit button.
Green Light If the light is green, the applet is waiting for input. Red Light If the light is red, the simulation is busy.

Configuration Menu: Many more features of the simulation can be controlled through the configuration menu, which is accessed through the configure button. Upon pressing this button, you will see a menu with three choices: Hysteresis Model, Loop View, and Lattice View. The latter two allow you to change some properites of the display. The first allows you to control all aspects of the model.

Under the Hysteresis Model menu, there are seven options:
Goal Field Enter numbers here to precisely control the external magnetic field. When a number is entered, the magnetic field will be slowly increased until it reaches the entered value.
Disorder This sets the degree of disorder in the lattice.
Dimensions Use this parameter to adjust the dimensionality of the lattice. Any number of dimensions greater than or equal to two is valid. (But higher dimensions will take much more memory, and run much slower.
Width Adjust the width of the simulation. Any number of spins is valid, but the larger the simulation, the slower it will run.
Seeds Up This creates a single row of spins preflipped to point up. This facilitates the seeding of the first avalanches in two dimensions, and drastically changes the effects of the finite size of the simultation. This option may be true or false
Seeds Down This has the same effect as the Seeds Up option, except that the row of preflipped spins points down. The two options can be used simultaneously.
Lorenzian When this option is false, the simulation uses a gaussian distribution of random fields. When this option is true, the simulation uses a Lorenzian distribution of random fields. Because the Lorenzian distribution decays much more slowly than the gaussian distribution, there are many more spins with large local fields to seed the early avalanches. Right now, it is necessary to zoom in on the hysteresis loop when using the lorenzian distribution, because the interesting behavior occurs in only a small fraction of the range of fields.

What is hysteresis?
View the source code.

This page last updated on Sunday January 5, 1997.

e-mail: mck10@cornell.edu