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Curie Temperature

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.

Pierre Curie
Pierre Curie (Source)

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.

MaterialCurie Temp(K)
  Iron10437701418
  Cobalt140011302060
  Nickel627354669
  Gadolinium2921966
  Dysprosium88−185.2−301.3
Manganese bismuthide630357674
Manganese antimonide587314597
Chromium(IV) oxide 386113235
Manganese arsenide31845113
Europium oxide69−204.2−335.5
Iron(III) oxide9486751247
Iron(II, III) oxide 8585851085
NiO–Fe2O38585851085
CuO–Fe2O3728455851
MgO–Fe2O3713440824
MnO–Fe2O3573300572
Yttrium iron garnet560287548
Neodymium magnets583–673310–400590–752
Alnico973–1133700–8601292–1580

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.

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

What is Curie’s temperature?

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.

Is Curie’s temperature the same for all magnetic materials?

No, Curie temperature is different for different materials due to their properties.

What is the Curie temperature for barium titanate(BaTiO3)?

The Curie temperature for Barim Titanate(BaTiO3) is 120℃.

What is the difference between Curie temperature and Neel temperature?

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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