Curie Temperature (\(T_C\)), also known as Curie Point, is the temperature at which certain magnetic materials undergo a sharp change in their magnetic properties.
This point was named after Pierre Curie, who showed that magnetism was lost at a critical temperature, in 1895. Pierre Curie also gave Curie’s law which connects magnetisation, temperature and magnetic field.
Index
Curie Temperature Explained
Curie temperature is the temperature where the magnetic materials lose their permanent magnetic properties.
The Curie point varies for different magnetic materials.
| Material | Curie Temp(K) | ℃ | ℉ |
|---|---|---|---|
| Iron | 1043 | 770 | 1418 |
| Cobalt | 1400 | 1130 | 2060 |
| Nickel | 627 | 354 | 669 |
| Gadolinium | 292 | 19 | 66 |
| Dysprosium | 88 | −185.2 | −301.3 |
| Manganese bismuthide | 630 | 357 | 674 |
| Manganese antimonide | 587 | 314 | 597 |
| Chromium(IV) oxide | 386 | 113 | 235 |
| Manganese arsenide | 318 | 45 | 113 |
| Europium oxide | 69 | −204.2 | −335.5 |
| Iron(III) oxide | 948 | 675 | 1247 |
| Iron(II, III) oxide | 858 | 585 | 1085 |
| NiO–Fe2O3 | 858 | 585 | 1085 |
| CuO–Fe2O3 | 728 | 455 | 851 |
| MgO–Fe2O3 | 713 | 440 | 824 |
| MnO–Fe2O3 | 573 | 300 | 572 |
| Yttrium iron garnet | 560 | 287 | 548 |
| Neodymium magnets | 583–673 | 310–400 | 590–752 |
| Alnico | 973–1133 | 700–860 | 1292–1580 |
Curie points for different materials (Source)
Before approaching Curie point, the material has permanent/spontaneous magnetism. Once the material is at Curie point, this magnetism is disrupted. Though, it can be replaced by induced magnetism (getting back the magnetic properties by applying a magnetic field).
Note: Here, Permanent magnetism is caused by the alignment of magnetic moments(spontaneous magnetism) and induced magnetism is created when disordered magnetic moments(due to crossing Curie point) are forced to align in an applied magnetic field.
The force of magnetism is determined by the magnetic moment, which originates from the angular momentum and spin of the electrons.
Below Curie Temperature 
Above Curie Temperature
Ferromagnetic Materials
Materials are ferromagnetic only below their \(T_C\).
Ferromagnetic materials have strong magnetic fields and high Curie temperatures(around 1000 K) as their interacting particles are aligned in the same directions. These are aligned in the same way even in the absence of external magnetic fields.
Ferrimagnetic Materials
Materials are only ferrimagnetic below their corresponding Curie point.
Ferrimagnetic materials are magnetic even in the absence of an applied magnetic field and are made up of two different ions.
Antiferromagnetic Materials
Materials are only antiferromagnetic below their corresponding Néel temperature.
The Néel temperature is analogous to the \(T_C\) for antiferromagnetic materials and this temperature is named after Louis Néel, a French physicist who explained antiferromagnetism for the first time.
Paramagnetic Materials
All the above three materials turn into Paramagnetic once they cross Curie point.
Paramagnetic materials are non-magnetic when a magnetic field is absent and magnetic when a magnetic field is applied.
Properties Affecting Curie Point
The following properties of a material allows it to change its \(T_C\):
- Type of material – Composite materials can change their corresponding Curie point; if the moments are parallel, \(T_C\) increases, if perpendicular, \(T_C\) decreases.
- Particle size – The particle size in the material’s crystal affects the Curie point; if small, then \(T_C\) decreases, otherwise \(T_C\) increases.
- Pressure – Change in pressure on the crystal lattice changes its Curie point.
- Orbital ordering – The Curie point is seen to increase greatly due to electrons being packed together in the same plane.
FAQs
Curie’s temperature is the critical temperature at which certain magnetic materials undergo changes in their corresponding magnetic properties. It is denoted by \(T_C\). It is also known as Curie Point.
No, Curie temperature is different for different materials due to their properties.
The Curie temperature for Barim Titanate(BaTiO3) is 120℃.
Curie temperature and Neel temperature describe the magnetic properties of certain substances. The key difference between these two temperatures is that at Curie temperature, the permanent magnetic properties of certain materials are lost whereas, at Neel temperature, antiferromagnetic materials become paramagnetic.
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