Chemistry Reference
In-Depth Information
Figure 2
Schematic phase diagram close to a quantum critical point for systems having
an ordered phase at nonzero temperature. The solid line is the finite-temperature phase
boundary while the dashed lines are crossover lines separating different regions within
the disordered phase. QCP denotes the quantum critical point.
by the temperature. An experiment along path (b) thus explores the tempera-
ture scaling of the quantum critical point. The phase diagram in Figure 2
applies to systems that have an ordered phase at finite temperatures. Some sys-
tems, such as Heisenberg magnets in two dimensions, display long-range order
only at exactly zero temperature. The corresponding schematic phase diagram
is shown in Figure 3. Even though the system is always in the disordered phase
at any nonzero temperature, the quantum critical point still controls the cross-
overs between the three different regions discussed above.
Figure 3
Same as Figure 2 but for systems that display long-range order only at exactly
zero temperature.
