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From materials to cosmology Studying the early universe under the microscope
Published on 2020-01-31102 Views
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From materials to cosmology Studying the early universe under the microscope - 100:00
From materials to cosmology Studying the early universe under the microscope - 200:12
Quiz01:47
“Standard Model” of Cosmology - 104:33
“Standard Model” of Cosmology - 205:33
Spontaneous symmetry lowering phase transition in a ferromagnet07:07
1. Choice of multiple equivalent low-symmetry states08:16
2. Defect formation at symmetry-lowering phase transitions - 109:21
2. Defect formation at symmetry-lowering phase transitions - 210:09
2. Defect formation at symmetry-lowering phase transitions - 310:13
2. Defect formation at symmetry-lowering phase transitions - 410:15
Defects in ferromagnets: Domain walls11:57
Spontaneous symmetry lowering at the Grand Unification Transition13:09
Different regions of the early universe choose different equivalent ground states - 114:19
Different regions of the early universe choose different equivalent ground states - 214:42
As the universe expands through the transition, the low symmetry regions grow…14:47
and eventually meet!14:50
The angle mismatch in the low-symmetry vacuum is a topologically protected one-dimensional defect (Kibble)14:53
A detail: How many cosmic strings should we have? 17:31
Do cosmic strings exist? How can we study them?18:55
How is Cosmic String Formation at the Grand Unification Transition studied? - 120:03
How is Cosmic String Formation at the Grand Unification Transition studied? - 220:37
Instead we will study the GUT in our laboratory!21:03
Where to find a suitable material? Multiferroics: Multiple ferroic orders…25:12
…and multiple defects from spontaneous symmetry-lowering transitions26:51
Our material: Multiferroic YMnO3 - 127:31
Our material: Multiferroic YMnO3 - 228:59
Look at these distortions in more detail: - 132:39
Look at these distortions in more detail: - 234:21
Calculate the form of the potential using symmetry analysis and density functional theory35:04
And the details of our “Mexican Hat-like” potential make it easy for us to measure! - 137:04
And the details of our “Mexican Hat-like” potential make it easy for us to measure! - 237:21
The meeting points of the ferroelectric domains are in fact one-dimensional “strings”38:10
The structural phase transition in multiferroic YMnO3 provides an analogue to the Grand Unification Transition38:27
What experiment would we like to do on the early universe?39:51
Testing the predicted “Kibble-Zurek scaling” for defect formation42:41
Comparison of predicted Kibble-Zurek scaling with experiment44:42
”Beyond-KZ regime” and unexpected dependence on chemistry45:52
Open questions:46:51
Summary48:22